Report Na.

Report No. 64
64

~
'rn -'~ "‘
GOVERNMENT OF
GOVERNMENT OF KEN YA
KENYA

MIN ISTRY OF
MINISTRY OF NAT URAL RES
NATURAL OURCES
RESOURCES
GEO LOGICAL SURVEY OF
G'EOLOGICALSURVEY OF KEN
KENYAYA
/'

I,
GE OLOGY OF
GEOLOGY OF TH
THEE
EL DORET AR
ELDORET EA
AREA

DEGREE SHE
DEGREE ET 34,
SHEET 3:4, N.W.
Pill-V. QUA RTER
QUARTER
(with cnlflu red geulfl gical map}
(with eoloured geological map)
by
by
I
L. D. SANDERS, H.511, Phil, F.G.S., A.M.I.M.M
L. D. SANDERS, B.Se., Ph.D., F.G.S., A.M.I.M.M..
Chief
Chief Geolu gist
Geologist II
I
I

I:
I
I
—

Fifteen Shiflin
Fifteen gs -- 1963
Shillings 1963

I
 PURE“ D RD
FOREWORD
.. _. r _1 ... ‘ 1- L. LL... L
111+: E1L111z'L1
EIdoret Lir-L'LL 1.11 mainly
111311111}. agricultural
LLLI1LL11LL1FL1 in .11 character 11L1 minerals,
:1':111L':‘E115.L 11_._:L:11I
1

The area is 1.
JL1L1L.L and
...—...:—
L-IHLL. .111IL1 so .111 farL1. no apart
from 1:1.1‘-.-:1'i:'_11s_. have
12L1111111'11LI1L111'11 materials,
11111111 constructional 111111311311. 11'L11'1LL'L1 in
been worked 1:1 it.
31. The111L- geological
gL'L11.1:12:11} survey_ described 1::11::1:1L11'L1
......

1:1 the
in 131:: report
1'L111L11'1 indicates
1L11LLLL~L that 111'111 because
1111:111: 1': ofL11 the 115111.: 1'11 of
1.11:. nature 111' !the
111-: rocks, 1:31:11: mineral
1'L1:'L-L:~:. little 111311111 can
71:111.:1'1'11 wealth 1:111:
11L: expected
be 12-1." 1111121: 1:1 in111 the 11 1:11. AboUit
1111: area. 91111111: half 11:11: of
11111it is1'11 covered
121.11'L11i13'11 by
11} barren
111111111 young '1-‘1'11.1ng1111':13.
lavas, 111111.111
which hide 111111;.-
older .L11:1-L~'~_111."1:11.
1311;11:1‘ rocks that might 1.1..
11111.111 1. contain mineralsr‘ 11111:: The
of value. '11:”: exposed
L1L‘L111'1r'1L'1Li older rL1-:115 in
1.1111131 rocks 111 the 1111:
11111111 -L.1111111111 part
north-eastern 11111:” of111’ the
.1: area
.1
'|. :1:'L'1'1 are,
:-1.:. however, of a ,type -that Enid 131.113 that
.111 indicate 1.11111 11:111111151
131:1: only deposits
L11" non-meta:tlic
of 11111115111151. such
T:1L1:1—111L11.11111: minerals, 1111111:- as kyanite111 and
1:151:11ELU'1'L-111:
:11: gamet, graphim can
:1L1 graphite, 1:111 be L1:_11L1:1e11. Some
111:. expected. 3111111:
11131111111131 of
deposits 1'11" such 11111—1L‘1'111F; are
111L1L'11 minerals 1111131111 and L111;
:11: known L113...C1 1.1:?.11 in
are described ':1 the.11: 1:11111'
report.
The 111.1111
111-: older rocks 1.111 the
11.1-L11L'5 on L'L:.~1'1*L.'.11:1 traces
11:11. contain
111:: west 112115131 of 5.1111 and
U1 gold :11:L1 the
111-: tin
1f:1 mineral 1111:1111. cassiterite,
1:112:1sL21'1'LL’L
1::1111L deposits 11111311111 11111511311
1'1: ‘-L.. 1'21 :11 L112- seems
1
""1""1
-'L1L"::.11'1'L'.':L:L= of
L11"workable
_ -.-.._.-.. -.' -,.‘_ .-. —.-..1 -
HLl: the
but 1.11.1.1.- L111L.'L.11 are
11"“; occurrences 5L1L1'1 rthat
:LTL‘. such L1-L'. occurrence
1.11-1: the 1
unlikely.
The 1111'11-51'11-L'1'L11 part
T111: lava-covered 1.11111 of 111: area
1111’ the 111131. has good fertile 11.11111 soils 11111.1and the 1.11:. lavas
1111-1111 1:11:11111r1
contain
3141111c that
aquifers 111111 can 131111111 by
1:: tapped
L'.'-:11 be 1:11'1111:11g. At the lava edges the
1111' drilling. 1111:. water
'1'. 111L1r 111111-3111;
appears :11; as 1111-7111;;
springs,
and in
and 1-'1 other 11.11:». of
L'1L11L'r parts 113’ the 111L111 are
'_-'L:"L'-:1 there
11:: area '_=L."L: well-developed rivers. L1 .-‘1 section
A 1:313:11 of 111'" the
111-: report
r:p1'1:".
1»; devoted
is 11:11:1611 to 11.1 water-supply,
11:1161—1'111L1L111'. and :11:L1 the1111: flow11.111 of J..'_!.1C1:S in
1._11_ waters .11": the
‘|.. -.....
{11:2 lavas
_'._1’1'L'L'1~ is 1111151111131 by
1:» illustrated 111' a11
{111113111111
diagram that 111:11 will
11.11111: 115111111 in
be useful 11111111111111111.
planning exploration :1. [111.1111 111.1111 for
1111' subterranean
r11.1:11:1'r1111::111 water. 1131:
~ '
I
T11:
The first1111111 1311111115.;
editing 111’ of 111-:
the 1111.11.13.
;
script LL’J'
.5' .1 _
of the
'L._"11: report was' L"..-11:'
"Ifi'
carried
1L 4|1.9.11.
I“
L'L'L'L'1 1.11.11
'. 1.
1:";
out 1:11 by Dr.
'1'- -.-L T“- Dr. E. 1’. Saggerson,
E. P. 5111;935:111
1..L;- . —' fl..- __'- .-. ..r 1' .,-'.L..1 1:? 1.11 part
—~LL1-LL_L_-T. Chief
Acting 1: 1111.1 (ILL11121'5111L
Geologist, and 111111 the
L11L 11.1.11 LL1. 11111: in
final editing 1.1.;1'1'1:by'11:: '.1.1'-1'L:r. but
the writer, 111:1 mainly
111.111111'113' 131.1-
by Dr.
T1... 1.
N. J. (311L111.
Guest, Chief ($111131: Geologist.
(Licr11'LL.1g1111.

Nairobi.
Nairobi. ‘11 ILL 1 A511 PULFREY,
WILLIAM PLT LFREY.
11.1111. NL11'L11111L1".
16th November, 111611.
1960. 1’." "E11.1111.111.111.111'11' 1.11.1111'1'
Commissioner (Mines 111111and G1'-'1.11'1_l'.’5’.7"'1-
Geology).

}
k
 CUNTENTS
CONTENTS

PAGE
PAGE
A {LSLI‘LLCI'
Abstract

| --11‘.11'CLL'1L1C11D[1...
I-Introduction. .. .. .. .. .. .. .. .. .. 11

11—--13'I'L-L'1LLLLLL Geological
II-Previous GLLL1LLg1LLL1 WELL};
Work 3

IJJ
111—P113-‘51LLgrL1p11y
Ill-Physiography -- .. .. .. .. .. .. .. .. 4
4

—SLLLLLLLLLLL'1L' of
IV-Summary 023'
LL1 (1201'
Geology |_
. . .. .. . _ _ . __ . . _ . 8S

1" -1_.1L':LL111.~':'L of
V-Details L'L1 CLLLLIL‘L
‘LJ.’ ..
Geology..
'I—J
.. .. .. .. .. .. .. .. 10
.1 U

1. Basement System.
1. Basement SL- LLLLLLL _ ._ _ _ . _ . _ _ . _ _ _ 1O
10
(11 Migmatites,
(1) CiraL‘LLLLfiL‘LriLLS and
1‘L'11 Ll‘1‘1Ei1.1[L:S Granodiorites AmphiLLLLh'LLs of
and Amphibolites LLF theL1H: Turbo LLLLLL
TurbLL area 12
12
(2) c.111E1C1E111-‘L11C5.1V1‘L’1E11'111L'35
.'_'1 Cataclasites, Mylonites and P113'11L11'111CS
LLLLL1 Phyllonites .... .... .. . ..
.. 16L
16
1.3.1 Metamorphosed
(3) SLdLLLLLLLLLLL‘fL' and
\IL*LLL11LLL1:L1LLL:LLL1 Sedimentary LLnd Volcanic I'LLLILS of
‘L LLILLLniL' rocks 011 the {11:2e—
L1LL Cheran-
gLLnihilis
gani hills .... .._. .._. .__. _. ._ _. .. 11:1
18
(4) I‘v'ILLLLLLLLLLplLisnL and
LL11 Metamorphism CLLLLLL-LitiLLLLLiLLLL ..._
LLL'LL1 Granitization _ . _ . . . . . ELL
26 .'
2. [LLLLusiLLL‘L
2 Intrusives.. .. .. .. .. __ _. __ .. _. 111
28

3. Tertiary
3. LLLL'LLLL and
TLLL1LLLL' Lavas Tuffs. . ..
LLLLL1 TLLL‘L‘S . . . . . . . . . . _ . 211
29
(1) ILI1L3LLLL=LTL1113
111 Miocene and (Brita
Tuffs LL1Ld Grits . . . . . . . . . . . _ 31.1
30
(21 Lower
(2) L. 3.3111 Gishu
LLLLL'LL' Uasin PhLLLLLLliL'LL
G151LLI Phonolite . . . . . . . . . . 3
31
(3) Upper Uasin
131 Upper PhLLrLLLiiLL
Gishu Phonolite
LJL'LL'LirL Gishu ._ ._ _. . . .. 3
32
L1. Recent
4. DLLLLLLLELLL
SLLgLLrfiL'iLH Deposits
RLLL‘LLLL Superficial . . . . . _ . _ _ . _ . 3
32

TI—SLL'LLLLLLLL
VI-Structure ._ __ _ _ _ _ _ . _ . . _ . . _ . . . .1
32

VII-Mineral [1121105115 . .
TL-"I1—i‘L-11LLLL'L11 Deposits.. . . . . . . .. . . . . . . .. 3L
38
1.CjL_LIL:5._
1. Gold.. ._ ._ ._ .. .. .. .. .. _. 3L“.
38
2..'1'1n._
Tin .. ._ __ ._ ._ .. _. .. .. .. 3:51
39
1-_}

1mm and
3. Iron N1 LLI‘LgL'LL'LEFLe
and Manganese . . . . . . . . . . . . . . 3'1}
39
«LL-LL:

4. Graphite ..
. (.‘LL'LLplLLLL: .. .. .. .. .. .- .. .. 39
39
K}-’£1I111L2
5.. Kyanite .. .. .. .. .. .. .. .. .- 41.1
40
UL

6..CLLLLLLL-L
Garnet .. .. _. ._ .. .. .. .. .. 411
40
G".

11111:...
7. Talc.. .. ._ .. _. ._ _. .. .. .. 41
41
QLLLLLiLL:
8.. Quartzite .. .. .. .. .. __ .. _. .. 41
41
(E

9. LiLnLLLLLLLLL ..
9. Limestone.. .. .. .. .. .. .. .. ._ £11
41
10. 13311351 and
10. Ballast RLLLLL1—L'LLLLLLL.
L'LLLd Road-stone. . .. . . . . . . . . . . . . 4.1
41
11. [31111L11ng-LLLLLL'LL3
11. Building-stone . . . . . . . . . . . . . . . . 41
41
12. \‘L-"LLLLL
12. Water ..
. . .. .. .. .. .. .. .. .. 43
42
H}-'L1rLL—L:1LL:LL'1L.'iL;L' ..
1'3. Hydro-electricity..
13. .. .. .. .. .. _. .. 47
47 ,I

‘L'IlI—RLL'LL'LLLL‘LLL
VIII-References. ... .. .. .. .. .. _. .. .. . L1H
48

II

.
 1 Lift S'Jfflsi'flflfi 2'11-
ILLUSTRATIONS
P111111
PAGE
1111111 of
15'1111-31'11111111111111111 map 11111 Eldoret
1.11" the 1111:11
1111111131 area 116
rm-
_1

Fig. 1.-Physiographical
|_

_ 1 . - ~ ~1... -1
.- .1 11111111 1‘9
Fig. l—E1111111111111 to
171g. 2.-Sections 11111111 the
111 show 1. 111111111 Surfaces
1111: Erosion 1.1 the
5111111111111 in 121111111.
1111* Eldoret area. .. . - - 1'"

-
111 thin
111-11111111111 of
".—T‘1='11111‘1151:11111: drawings 11111111111111
111111 sections 14
"TI

Fig. 3.-Microscope
U
IC‘

Fig. 4.-Microscope
Fig. 11111111111111 of
4.——11=11111‘1:151:-31111 drawings 11111311111111
111111 sections
111' thin 18
111 thin
11 11111-111311; of
1.—1'1-'Ii111"1:111:11p11 drawings 1111131111111
1113.21 sections 25
1.1-1
:11

Fig. 5.-Microscope
111'

H11. 6.-Structural
Fig. 1111111 of
1"}.— 5111‘14111'1111'111 map 1111111
12111111111 area.
1111: Eldoret
111' the . 33
. ‘11
1111111111111 of 11111111111111; and
111" bore-holes 111 the
111111111111 in
111111 springs 11311111111 area
1111: Eldoret .--1. -.- .- 43
-
"1..
'5'
'1'!

. .
Fig. 7.-Location HILL-'11.. . _ . .
If.
-1.

'.—B1:11'1:—111111: 1.11:1:11111151
46
—.|

Fig. 8.-Bore-hole sections .. .. ..

13.";
11:;

5.11c1i111111 based
[—1.31311111311111 sections 1111 bore-hole
1111211211 on 1111111
111:11'11—1111111 data .. at end
'1..-'

Fig. 9.-Geological
HQ
._

PLATES
PLATES
I}L.-"1T1'i 1
PLATEI
{11'}
(a) 811111}! F11115 . ..
Selby Falls. at
111." centre
{$1311 1. 2'13

1111 Falls
(b) 111 Nel's
141111111 at 31111111
NEWS Bridge at
111 centre
1:111111'1:

1’1...~"1TE 11'
PLATEII
{111
(a) Sargflit ROE};
Sergoit Rock at
111 centre
1112111111

35111-11111
1:11.11 Ndalat
(b) at
111 centre
{:111'111'1:

131-111. III
PLATEIII
1:11} The
(a) 311111111111 Cherangani
1111: Southern 1 131111 .
{25111111111111.1115 Hills. at CCI‘IU'L“
£11 centre

(b) T111: Kitale

{1'1} The 13111111
111111-1113- Plain. . at
“111 centre
CSIHI'C

111.111: 1‘11"
PLATEIV
15111111111111 L'1
11111 Soysambu
(a) .. at
111 centre
121111111:

(b) 9111111111111: in
12,111 Agmatite T111'3_11_1
111i111111111111, Turbo.
111 migmatite, . at
111 centre
1:1:1111'11

P1 ,3. T1,. ‘11"

PLATEV
31-11:111C1111g1111111311111:
1111 Metaconglomerate
(a) at centre
1111111111113
Black mylonite
1:11.11 Black
(b) at centre

PLATE VI-Folds
PLATE 1.51 11111111 at centre

131.111. ‘1-"11—F 111115

PLATEVII-Folds. . at centre

111.111: 1’11[—I_11"_1:1111'1_1:111 and

PLATEVIII-Lineations 1111111111115
111111 mullions. . at
111 centre
#1311111:

711
MAPS.1. 135-1

(31111111111u111
11
Geological 111111
map 111‘ the
1 of 12111111111 area
1111: Eldoret { 1111111211
111311 (Degree
_ sheet T1311” _ quarter);
3-1, N.W.
111111121 34, 111111111111; Scale
S1111 1.: 1:125,000
1 11.25.111.111 at 111111
111 end

"'"
.. __ _ ‘I—
 1-"11'HS'I'R1'111
ABSTRACT CT
'l'his report
This repprt describes
tieseti'pes 1—111 an areaarea of pf -approximately
appresitrtately 1,200 1.21111 square.
square miles miles situatedsituated 111 in
syesterh Kenya
western Kenya between the het'1'1eei1 111'111'11ships of
the townships elf Elt'lriret
Eldmet and 11111111 Kitale,
Ritale. bounded
111111111r1e1'1 by‘ latitudes
by latitudes
0° 11111"
30' N.111-1111(11
and 1°' ["11’
00' 311'
N.- and
and 1131' leaeittiees 31:1J
by longitudes 35° 1111"
00' E.E- and
and 3:1’ 35° 311’
30' E- Mast 111
E. Most of the
the area.
area
is .1e111111tt111tl
is agricultural e11111111y- st11111'11111113 between
country standing 11'etsseep. altitudes
altitudes of111 1'.-11111111111111.131131111eeha
5,500 and 8,000 feet, andttriprt'11'1uees produces
eereals- syattEe—bars.
cereals, wattle-bark, sisal.sisal, ee11ee.
coffee, sun—111.1ss'er
sun-flower seed seed and ps'rethrtih'i; stock
and pyrethrum; st 1'_1el~'1 1111111
and dairy
dairy
1'1'11'111111gare
farming are alse also 1111per11111t
important aetis'ities-
activities. ForestF111'e.s1eser'1-'es
reserves eeettpy
occupy ,the the highest
hiahe st e11t1-ittr'y
country in in the
the
11111'111—e'171st.
north-east.
The U
The 11i'1-1s111
asin Crishti plateatt. bounded
Gishu plateau, h1ii111e1'1 ,to
111 the
the north
111''1r111- 11y steep es1.
by steep 1rp111- 111s overlooking
escarpments 111111111211111113
1he 711111111111 11'11lle-y.artt1
the Nzoia valley, and 111 to the
the 111-est
west hy by sh'11-1ller
smaller 11.1113112‘3-‘11-1‘111111
escarpments 1aei11gr facing the the Sesiahi
Sosiani 1.1a ley. is
valley, is
ft1r11'1et1 by
formed 11y sheets
sheets of 1111‘ phQnolitic
pht11111litie 1111111.
lava aee1'111'1pa111etl
accompanied by 11y basal
basal tuffs ttit'Ts 111111
and grits:
grits; the
the 1'lavas
.-'1'1-"1-1s
entered
entered the the regionres-311111 1111111
from the the south-east
s11111h— 111st 111 great mobile
in great 11'11'1hiie floods
[11'-1111:1s syltieh
which spreatl
spread 111-e1
over a 1411

111.111pl-..1111 surface
peneplained sttrtaee in i11 Miocene
‘slieeette. times.
titites-
C 1st111l111e rocks
Crystalline reeks 1.11- the Basement
of the Basement System“11'-111.111 underlie
11.1.t1e1l1e the
the Uasin
Li'asir: lElisha 11=11-'11s 111111
Gishu lavas and are.are
als11 seen
also seeh over
111-er the
the remainder
1'e111a11111er of
111 the
thee area.
111e'1-1. The{he Basement
Baseiheh. System
System rocks
reefs-s are 1111'i11e-ti into
are divided 111111
two11 regional
re‘ 1—
er1111pz's .' —
groups:-
lb-

111 A
(i) 51111series
series 1111
of 11well-differentiated
1'l—111111111111111tt111 superincumbent
stipe 1i11ettit1he111 folded
1‘1'1='tlerl metamorphosed
111e1111111'1rpht1se11 seriititettts
sediments
111 marginal
of 11.1arg'1111-11l geosynclinal
1111111111111l11111 facies
1aeies occupying
11ee111111i111-3 the
the ele111-1e1'11 Lheraheapi region,
elevated Cherangani 1111111111111111
”[12: and iii]
(ii) aa
arattite i1tia1111ttite. foundation
granite-migmatite 11111 11111111111111 underlying
ttt1derly-1ttg thethe less
less elevated
elesatesti etitttttry
country aroundra1-111-111'1'l Ttirh111 this
'turbo; this
has been
has heen. subjected
stihjeeted to .11 syntectonic
ss 11ee11111111. metasomatism
111e1-1se111atis111 111111 sheari11113 in
and shearing 111 thrust-zones
thrt:st-.11_1i1es that that dip
dip
1.111111111111111 beneath
eastwards hehea1h the the superincumbent
st1peririettt1'1heh1 meta-sedimentary
theta-serlihietttary111111111
series.
111 the east’.
In the east, Tertiary
Tertiary 111'
or l’leist1'1ee11e faults conneoted
Pleistocene faults epitheeted 11'1'i1h
with rift y'alley 1111111e11'1ehts
rift valley movements
haye displaced
have displaeea both
[111111 lavas
las'as 111111 111etatitrirphie basement.
and metamorphic hasetheitt.
111:1 aee11tiitt
An account is is given
git-ea 1111'
of thethe petrography,
petrpgraphs1y. r31'_te111-1sis and
genesis 1111111 structure
str tetttre of
111the11'ari1'111s reeks.
the various rocks,
111111
and thethe ee1111111111
economice praspeets
prospects 1111111 syater resources
and water reset ees of
111 he area
the area are asses-1.1.11
are assessed.

..
-'
 OF THE
GEOLOGY OF
GEOLOGY ARE-A
ELDORET AREA
THE ELDORET
I—INTRODUCTION
I-INTRODUCTION

The area
The area et11ereti
covered 111' by thh;
this repurt
report eempriser;
comprises the the 11111'th-11-e1t
north-west quarter quarter ef of degree
degree 1heet
sheet
'34 (Kenya)
34 tIJireeterLLLe of
(Kenya) (Directorate Survey-'1; sheet
DL'erLeLLL Surveys
111' Overseas 1heet No. hetmdett by
1:19). 'bounded
Ne. 89), latitude-1;
hy latitudes
0° 311' N.
{'1' 30' 1111111"
N and N..:111d
{111’ N.,
10 00' and by 1L111L-11't11de1;_1.'1'
h} longitudes 35° 00' E. and
tit. ' E. 151' .111"
:11111 35° 30' E.E- It 11'; Ltppt'eximatett'
It is approximately
1,200 miles in
square miles
1.21.11) square extent and
1'11 extent 11nd]lies L11;tr1'L!e. the
e11; astride L'LL1.1'11 Cli1h11
the Uasin Gishu and Ltistrietrt
'1 rLLnL-Nzeta districts
111111 Trans-Nzoia
het'e'eett Kitale
between Kitele at 111 the
the north-western
11L1rth-11'e51err1. corner,
center. and and Eldoret
Elderet at :1t the
the 111:11hL
southern 1r11 httLiI‘tLhtt'1'.
boundary.
Part of
Part L11" the Nandi reserve
the Nandi extends into
rer'LerLe extends the region
into the 1.1e1;t L1t'
regiett west of Bldoret, and the
E1L1L1ret. 111111 eastern11 mere-.11:-
the eL11tet margin
it'e1' in
lies 111 the 1-Ilge.}'e—T\-ttttat;:11'et
the Elgeyo- Mamkwet district.district.
.‘1-1'.:;',r.1..1'. 'I'L1p1'1grttph1ee! 11111111;
Maps.-Topographical maps referring
referring to 11.1 the
the rL'L'..L111.
region LLI'e'—
are:-
]:51"|1'.'J.l'.'tt'|t1.
1: 500,000, Kttt-tte Kitale E..—\.F.E.A.F. No. N11. 1717 17]? 1111—11111.
(1946).
North-.1311
North-A36
1I:.1it"'t.t..I11'_'HI.1.
: 350,000, Degree Degree Sheet, Sheet. Africa-\t'1'iL:11 —--— {5.9.6.5. No.
G.S.G.S. 17111.1 111.1271:-
N11. 1764 (1925).
\
X
1:|:IEtIJJIItt'I'Lt.
250,000, Cadastral (1111311111! (Special)
1511eL'iL'LI: Sheet
Rhee". No.1.
N11. 1. Eldoret.
HttL1t'et.
Nt'tt‘thahhh
North-A36
I
1|:{1Z.Ft'ltt.
: 62,500, CLLL‘LLLrLtru‘:
Cadastral Sheets Sheen; - ——- -—-- {L1. lb,
la, lh. lc
EL' L'and
1:1L'_I ld.
1L1.
X
1:511111111.
1: 50,000, PreliminaryI-1 'eLitt'111tL11';L- Plots
Pt-L1t1. 111.91.
89/1, 111.)
89/II,11. 541.1
89/III111 111111
and 111.} 89/1V [‘1' 1111.11.11.
(1958).

DLJr'Irtg the
During 1;11.r'1.e1.' geological
the survey "I plotted L111.
1.1111; plotted
:111'L11'111L111'1111 was
e11I11gtL'L11 information L'Lft-phL1LL1L11'L-‘1ph1 taken
on air-photographs t..-..1.e11
7‘11]. 82
17'} No.
by Squadron of
HI Squadron L'. the !1L.L1;.LLE Air
thL Royal
.‘J'
1 [-ILtrL'e in
.-"\i:' Force 11.1511. 911111
111 1950, and on 1111 1: 62,500 eL1.Lht1‘.1':-1t
1112.51.11} cadastral
tiehi-eheets. The
field-sheets. "the final 1111:.1! map111L111 is hL11'.eLt L111
.".1' based on the Ltpp1't‘1p; '1LLte LLLLJL111L11
the appropriate cadastral sheets 111111L11'
1.11111. minor
She-:11 with
1111Ht'Etth'1111 and
modifications LLLELt-tLL1tt1 Ltel'it-‘eLt
L—‘ttt-Li additions derived from 17:11:11 thethe Ltit'—[‘.hetL'1-L_‘11'111.1111.
air-photographs. Contours are based
(-1111111111'3 are '11- '
the L1L'111111L1teLI'7
L111 the
on computed heights hejehtr: L11" 111:1_§'L1r' and
of major L111L1 .1;eeL.111LlL1t"_-.' trigonometrical 1.1LLt:L1t1.1;.
secondary t:'igt1111.1111.e;':'e:1'.' stations, bench-'tt-L-L-L'h—
111111111 on
marks 1.1111 the Kenj-.':1—[_.Tg:-1tt::ht railway,
the Kenya-Uganda 1':.1it'-.1LL1j-.. and111111 barometric 111t1t.-he:eht.1;..
11:11'11111etr1e spot-heights.
FIJ”L’LL"'1J" and
Population 1.21.111" (LL;
Communications.- The The greater greet-.11 part 1111.“: 111
of thethe region
T'L'Llinrt is .1 a European
E111'=1.‘--1‘=e--.11
farming 11115111311 in
eit1tttet situated
tertittttg district what was
111 what I'L':1'111e:'ig.' 'an
11:11 formerly 1:111'1'eejttettted gees-1111;
L-Lt1. unfrequented grazing area 111mg
L11'e:1 lying
between Cher:1111_1:1t1I-nj.L1 tribal
the. Cherangani-Elgeyo
t1L‘it'11'eei‘. the -_-11'eL-11' L111Lt
tt';l.1;Li 'areas and the :11111 is
ht11'tlerf- and
\L'L-tntti border,
the Nandi htLtteihe-fi
1.1 margined
hf; the
by the Elgeyo-Marakwet
1:1gC1'Ll—I‘11111'111h1‘.L“. reserve
:‘e.1.er'-.e in11.1 the
the east,
ett1t. the the Nandi
N:‘111L11 reserve
1'e1'er1. e in
111 the
the south-west,
:1L111‘..- 1e1t. the ..-n_

Cehttttl :11111
Central North Nyanza
and North 511:1;11'1 reserves
1'e1e1'1e1 in 1:1 the
‘..'1e west,
1.1 e11. and
Let-:1 thethe Suk
11:11: reserve
1'e1er'1e in 111 the
'3'te north.
11L- th. R.-

priheitt towns,
The principal
The 11111111. KitaleKLLELJe and EELh1ret. are
L-tttLt Eldoret, '-‘1;'e exeandtng 1111.1111eit1LL'11t1e1. Eldoret
expanding municipalities. EldLh'et is 11;
aL1 principal
t11'1hL'1pL‘L 1tL‘tt1L1tt L111
station on the the Kenya-Uganda
HertggL-‘1—L'gL111Lt'L-1 railway 111111.111}; some 11-3111: 237 23? miles miter. north-west11.1.11'th-1t'e1t of e11
11 31111: Kitale
."1'L-1.:1'.. 111' while
Nairobi Hitttle is 111114-113: to
1.1 linked tL1 the Hett'LL-Lfgettdzt line
11111111 Kenya-Uganda
1'.-"1e main line by '11}: a:1 branch 1'L;;|1.L-.1-_-.
h1'1111eh railway
reheat-11111: northwards
extending 11.1;1t‘t}1.'-.1'L11‘LE:1. from
111.1111 Leseru.
I.e1er11. Both Berth towns 11111111; have hL11.'e railhead
r'LtilheLLLI installations
11111111ih1t1111t1 including 11L1L1L1.g
111111131. godowns,
sidings, gt1LlL1'LL'111. and Ltzttt stockyards
1.111L'k111rtt1; L11; as well '-.1e.-;' asL11; the the usualt11'L1L'1l township
1111111111111 trading trading facilities
111e1:'1.e1.
:111h:':1e111g banks,
embracing hL—tnk1. a:1 post 111.11! Ltthee.
office, .1.hL1_L11
shops 1'and 11 111 garages.
e115'11_1__1e1. ThereThere are are 111111also schools, .1;L'hL111§.11. recreation'
l-I-.I.L.—l—_._.__ -'."I
5...! '..—L- __.1_ l

-L".-L1h.1_ and
clubs, L-Lttti aL-‘1 hospital
111111111111 within 'L-thht the the township
'.L1'-.'-:'1ht '-.':e1:111i1::1. Smaller
vicinities. E11111-111111' trading
t:'L-‘1Lht'1L1 centres
L'e11.‘:'e1.:'-11'e
are
-_J

situated ttt
1itttttteLl H01"- ‘1. Bridge
at Hoey's Bridge and 11:10. Soy SL1}. L111 on the the Kitale hrL111L'h railway,
1111;.itL1T11 branch and 111
r'L-‘11h.'.'-11..'_L'. 111111 at TL::'E.1L1
Turbo
L111 the
on the Kenya-Uganda
Kett'.‘ :1- L. L_1.L1=.1.:1L1 railway.
1'L11§'-.'L':-11.'.
"there are
There are as L11; yet
1. L1.: no
1111 tarmacadamized
t111'111L1L-L1LEL1L11EL'e-L'. trunk
111.1111: roads
1'L'-:1L!1: in1'11 the
the district,
Lh.1.trtet- but
hL1'. this
11.1.11; part
11L11't of 111'
the I_.'L11E;t Gishu
the Uasin (11.1.1111 Lt;1:i
and T1'L1:11.-‘.“1§1'L1'IL1
Trans-Nzoia is f1. 1e1'1eL1
served L1}; :1a network
by her-1111'}: L1t' of 11etl tttLtftttailteLt' 12"."t
well maintained earth
"L'IttLt1. important
roads, :':1111L111L111t among
L11111: .'15; which
1.1'ht'L'h are
L1.:'e the
the Eldoret-Turbo
I-II-LEL1:'L1t1'I'.'.:'hL1 section
:1eet111 of 111' the
the main
1111t road r11111:1 from 1".111';
[.1.-:1 :‘et to
Eldoret 1L1 Uganda,*
L.g:1:1t::1."' and :-.:1-:1 the
the Eldoret-Kitak
E.L.tL'-1'et-i~L.'-LL-1‘;L' roadt.
:'-L'1:-.:"'. Other
Other roads 51:11:71: extend
e1t:.".1_t northwards
1‘.;‘1L'Lit'-.'1:-.:'Lt1
trL11'11 Eldoref
from E1L1111'et to 111 Kamorin
1131111111111 :111Lt TL111'1hL1eh 1111
and Tambach on the the Elgeyol-tlgete escarpment,
e1e111‘ptttettt. and L'11111 also
L11111 to tL'.
Hel'gL'fit.
Sergo ‘11L'1r't1e31. Kamna
it, Moiben, E1'LL11'11:1:1 and 11:.1'L111L11'et- 'I'here
and Marakwet. There L'Lre are air L'LIJ‘ :111'1'111;
strips at Ltt Kitale
Kitete and LtttLt F!-.1L11'e'..
Eldoret.
ilk-.1: Ft'.;1...,'"_11_h1_."1'1EF
* Part macadamizedL‘L-E December,
I3L'LLST1CL'T. 1"”..“2'.
1963.
t" 19111.
71.].te:'1-:"_-.Lr11'1.1'1:-L1 1963.
Macadamized

,..
. -- -
 2"t

lr'egettrtirin and
(Jiiri'irrte, Vegetation
Climate, the Eldoret
Frrrrrttr.--——:"‘tlthutigh the
and Fauna.-Although vvithin one
lies within
area lies
Eltitiret area tine
degree of
degree at thethe equator, temperatures are
dailv temperatures
etiuattir. daily inederate and
are moderate and the Climate is
the climate etitiahle
is equable
thrnug‘nnut the
throughout the year, mueh of
sinee much
sear. since at this part. of
this part stands at
Henva stands
nil Kenya at. an altitude of
an altitude there-
at more
than 6,000
than feet above
t'i.tlt‘it} feet Raint‘all reaches
sea— eve]. Rainfall
ahnve sea-level. during the
niasirnuni during
reaehes aa maximum nianths of
the months at
April. lie-lav anti August. tvhiist Deeerriher. lanuarv
April, May and August, whilst December, January and February are the driest and l-ehrttarv are the driest
months. Some
months. temperature and
Same temperature rainfall statistics
and rainfall given in
are given
statisties are Tahle 1.
in Table I.

I -"Irstirrit.srt:tr AND
Tat-STE I-TEMPERATURE
TABLE lt.-ttsi..tii. IN
.s‘sn RAINFALL 'I'HE ELDORET
rs THE Assn.
Ei_:'_itisrr AREA

it"r'nrri‘s of
("titan records
(from the East
hf the _-al_t"i'rt‘r:"t.-' Meteorological
East African De,ini'tnre'irrl
.‘i-fe'reiiii'rrilttgri'enr' Department)

Rsts'tzsttt
I . RAINFALL
1.

He. of
No. years
at years Mean t1."| nual
Tvlean annual Mean
Mean lit-lain
Mean
Statien
Station reeurded
recorded rainiaii
rainfall wettest ntnnih
nettest month driest innitth
driest month
tip to
up 1"}5?
tt'i 1957 tin.)
(in.) tin.)
(in.) t__it‘..}
(in.)
I
lsitale ..
Kitale .. .. an
40 atrial
50.18 Maj;
May T-t’il
7.61 J an.
Jan. t1 35
0,85
Elderet
Eldoret .. ,. 9E1 ill-2L]
40.29 Aug.
Aug. 6-37
6,87 feh-
Feb. 1 till
1.01
Tu that ..
Turbo .. .. Ill
31 ‘71 l 7.37
50,77 Ft ug.
Aug. “'3 ‘3‘}
8,39 Jan".
Jan. [ll-Sh
0'86
Hoey's Bridge . .
liney’s Bridge.. .. .li
31 ill-22
48.22 Au"
Aug. “ti-‘2}
7,69 lan
Jan. iii-E18
0,98
Stay
Soy .. .. .. ill
41 we'll
46,71 ..-"'~tti~r
Aug. #34 Jan.
8.34 ll'h‘i
0,95
Cl‘ierai‘igtuti
Cherangani .. .. 34
34 42-35
42.85 .lul'w~
July 6,65 .lan.
s-es Jan. U-TT
0'77
\‘ltiiljert ....
Moiben .. .. ltl
16 “an"
38,87 April
April 6,76 .lai
45' Fti Jan. [Ll-Era-
0,64
I

Tittitrritsi Lite {Degrees

'31. TEMPERATURE
2. kaltrenheiti
(Degrees Fahrenheit)

No. vea rs
n I‘ years
:‘s' e. of T's-"lean
Mean .‘s-"Iean
Mean Highest
Highest . Le v. est.
Lowest
Siatit'iit
Station retarded
recorded mttsit‘nurti
maximum IlllllllllLllTl
minimum n‘n‘tsittiut'ti
maximum minimum
minimum
up to
up 1957
tn 1957
--

liitale
Kitale .. .... 55. Th3
78,3 fit—i ‘71
50,5 as:
89.2 3.95
39'5
Eldnret
Eldoret ... . ... . 10
10 73-9
73,9 4‘} 3+
49,4 37rd
87.0 iill-ll
40.0

elirnatie environment
This climatic
This indtiees the
envirnnn'tent induces the natural at" aa tree
grnt—t-th of
natural growth savannah over
tree savannah nver
intieh of
much tlte region,
til the vvith agricultural
hut with
reginn. but develnpnient the
agricultural development hush has
the bush prngressivelv
been progressively
has been
eletired and
cleared and land plaeed under
land placed pluugh. so
the plough,
under the sn that
that the eharaeter of
eriginal character
the original til" the eetintrv
the country
nnlv be
ean only
can seen outside
he seen the arable
nutside the areas. It
arable areas. evident from
is evident
It is [rum these areas. and
these areas, train
and from
the aeeeunts of
the accounts the first
at the settlers to
first settlers tn arrive
arrive inin this part at
this part of Kenya, that much
Hens-a. that til the
rntieh of the
Gishu was
Uasin Gishu
Uasin tvas formerly vei’tt (grassland
ripen veld
ternierlv open with isolated
tgrassland with tree growth),
isnlated tree the
vvhilst the
grtnvt'hl. whilst
enuntrv of
let-v country
low at the h'lnihen and
Nadia. Moiben
the Nzoia, suppntted aa denser
vallevs supported
.Seisfani valleys
and Sosiani thnrn—
denser thorn-
bush at deeidtietts
strips of
with strips
hush with deciduous and evergreen tnrest
and evergreen near tn
forest near the n-atererittrses.
to the watercourses.

In the
In nnrth—east of
the north-east the area
at the the Cherangani
area the hills rise
Cherangani hills steeplv to
rise steeply eseeeding
heights exceeding
tn heights
9.00131 feet;
9,000 in consequence
feet; in here is
rainfall here
the rainfall
ennseriuenee the is considerably higher than
ennsiderahlv higher the
ever the
than. over
Kitale plains
Kitale and Uasin
plains and Gishu plateau,
Uasin Gishu sn that
plateau. so the higher
that the parts of
higher parts Cherangani
the Cherangani
at the
are clothed
are in forest
elnthetl in limited timber
enntaining limited
terest containing reserves of
tiniher reserves pndn and
eedar. podo
at cedar, niised
and mixed
llambne thickets
hardvveinds. Bamboo
hardwoods. are abundant
thiekets are aheut 8,700
ahnve about
abundant above feet.
5.3-1}t feet.

___._._..aa—-- 1—
1.!oOo
 3

I);
The entire
The entire area area supported
:tuppeirted aa rich rieh fauna t'auna at at thethe opening
ttpening of 1'11" the
the present
preaent eenturt'.
century,
and the
and the UasinL'aain Gishu(jithu plateauplateau atferdeti
afforded aa natural natural heme home for t't'Ir e1ant1.
eland, impala.
impala, II-Iiiderheeat.
wilderbeest,
httt'teieeeat. zebra,
hartebeest, I1111t'111e1' gazelles,
the smaller
:Irebt'tt. the reed-1:111:11. ostrich,
gazeliea. reed-buck, girafi'e. eheetah.
I.I.Ittrie1. giraffe, cheetah, lion 1111.1
111.111 and
11111111111 whilst
buffalo, the more
I.I-'hil-Itt the mere densely Ieeetated areas
ttenaeh. vegetated I.IttpptIt'tet1 baboon,
areas supported hahtItIi-I.n11.11111ey.
monkey, leopard letIpa1'11
and .1I1I1eI...eI-. with
and rhinoceros, e1ephant in
I.I'ith elephant in the :"tIreItt areas.
the forest areaa. The impreaaftIna of
'I'he impressions 111 the late C'eeii
the. late Cecil
Heey on
Hoey arriI't'ttg at
1.111 arriving Sergeit Rock
at Sergoit Reek in En 1906 1I.‘It'iIIT.i leaves one in
1e.a'1'e.It one in none doubt eetteerning the
t1euht concerning the I
former ahttntianee of
t'nrn'Ier abundance 1111 game
game in thia part
in this part of Kenya “"I‘It'eI'er shall
e1 Kenya-"Never pitching
ferget pitching
5111111 II forget I
my first camp
111:: first ean'tp there there £11111 and seeingSeeing the thtItt'Itant1I1 and
the thousands thturrtantfla of
and thousands 1I1 game
game roamingreaming:
eI'er the
over the plains hettIeet‘t the
piaina between Eige' n forest
the Elgeyo t'tIreIIt anti and the the Nandi Prnhat lions
haru'er- Probably
T‘IJttntii border. lie-KI
were mere numerous
It'ere more .1......_.I-t-. in this diatiiet
in thi-t district than than mmt- most, to ttI say ntIthint: eIt'
.I.-1:; nothing of eiephant
elephant and the
111111 the
mine. I.I.hz'
rhino, which eh one eIIe .t'etIIIIIttt-1.1
encountered in in considerable
..Itjtt-Iieert-ttI-‘ie numbers"num'eet'I” (Hoey, I'Hee::. 1955).*
1'-1.‘7.“'I."'
the h
'l'ntiatI the er'ts. 1111' I'
Today herds of gamegame hate disappeared apart
have diI'I.I'.tppeat'et1 apart trem from Itmaii small numbers tun'Ihei'It of reett-
ni' reed- I
buck and aa few
1.11.1121; and girali'e. In
1e11' giraffe. 1:1 the '-.I.'.Ii.'ItieI..l valleys
the wooded 111aI111.-.I:. and
t;1'.t"1-.e1'. monkey
1.1-11113:.‘II duiker, haht‘It'Itt are
ahei baboon -.-.';-.'.--;'.
are seen
_.._.. .. ._...—.....; .-t:.i. .I .
.I.-. hfltIi .... . .: .. .'..i. '_,..I. .I.
11.1..1It.1.1..1:..ant1
occasionally, and ..tI..I.t.I..-
leopard are shot or trapped.
.I. trapped 1....I-n1-'.ittteI.I.I
from time to time. 11.1w.
I..11-.e. Birds I11-...II.:.i.-.
including -i_

tranettlra. guinea-fowl,
francolin, .'.—anew: and
It.1Iit't'In1.tI.I cranes
gttjttet-IITtIIItz. kavirondo ‘111'1111’11e‘rt 1.1:'
Ite'teral varieties
ant. several of duck '.tre etIrI1n1.I:1-
1:11t are common.
11’.I'.1.I'.I.I.IIII.I of
History ..t....I,III .It-Itt. The first
I.If development.-The etInaiu'erahie influx
heat considerable i:111u.I; 1'of .IIettierI. into
11" settlers intn this thin: region regintt
ttIeI1. place
took plate in 11.11.'I:I—1I.11'."|1'.I. and
in 1905-1906, It]: '.i.'aI. 11.11“: of
11111.1 cultivation wheat anti
1:11 I.I'1Iettt and marge maize begain heettftt on en aa 11111111—Iea1e.
small-scale.
The prevalence
The pre't'aiettee of 1'11II: in
I.II' rust II I1‘I' caused
I".1 wheat e:tt'.IteI'.1 many 11115111}. early e;".I'.'i:.' crop 1;.111:1'e.II: until
ctr-:11 failures .I'ttIIt-t'e.-~5~-:.'tt":
1:11111 rust-resistant
'.I.
...-u- ..'-.- - -..---t.-| . -|I.-.'1-',-- .'-- I 1--_--.' .- 1‘
I.._-1_.fl.1LZII-
varieties
'i
DCL..I.11I.C
became 'CTII'..'1.T"...II§_|I._‘..1
established .:."I. a
as .t :I._.II...1.
result 11-.
of l'i‘IttlL‘.i'.-.t'_‘IIi
researches _‘ .11
at 111'.“ Njoro
the . 1111'.“ 1111111131'11'11C1'.'.ft:
experimental
attttiett near
station tteitt' Nakuru. HahnI'.'u. Difficulties [1113111111115 of I.'.tI;'1-.-:'Iett:'ir;:.j were
.11" stock-rearing t'iLttIIe1'-.':-t'..I.'. East
'-.I.-.I:'e numerous; E.'I..~.'. Coast Ct‘ta:-.t fever teI-e
attaeiItett imported
attacked in'tpttt'teti eattie cattle reducing redueing their their numbers I.IttntherI-I almost L‘.1111I._II~1. to tn nil,nit. and 1:.111p1tttngiita1tiiee
11111.1 lymphangitis killed
t11at1:.' horses.
many ht'Iz‘IteIII. Fencing FE't'tIL'1Itj-1‘I was I.I..tI. hard111-1111 to 3111-1111I'.:-1'.I1 in
tn maintain t1iIIit'fe: populated
111 a:t district 11111111111111. 1.13% by large arge herds he 2"1.1~ tI' of
.Itehra.11ht-.Ih
zebra, which were I.I... often «htntpgjeij by
i:1ItI.11 stampeded r.I_-. lion 11111 a. at night. 11;_I.-h-..
1:1 1907
In 1111111" a .'1 PostPeat Office 1.1311: was e.I_I2'I.'.'I.':_‘I.1.I_:.hei.1 on
I.I.aIt established t'I11 Farm 1":1'111 No. T‘Iih. 64. 11—1. A Iii-.111'ittttaa11111.':"'--.
11111-111'1U1 Commissioner's
:1. District
I5.11111ee and
Office 111111 Police Pt‘Il'iee Post tIItI. came ..'ttme into inttt being heme soon {111'13'111I1'L1‘1111'1L1
53.11111 afterwards, and at '.‘t'. a :11ee1111e: 1.11
a meeting atttt1erI.
of settlers
e.ti1ei;i by
called 11:. the the Governor, {—11.1-"1131‘1'1111'. Sir F’et‘e. Girouard,
'5-111' Per~y {—'111111L111i11. it was 1.1eeieie11 to
11.1w decided .1111111: the
tI.'I name rheasite 1111113112
..'.te Eldoret.
1111'.I.I:'t1:. before
Shortly he5113:. .I. the the. 1914-18 11111-131114: war, A. :11. C. 11113111114111. Director
{.'. Macdonald, Direeter of .-‘I.I:I.'1'f'.'=.t1tt.'re. in
1.11 Agriculture, 11'.-
.'.I.I‘-.'1p-.’-'.tt:.' with
company 111111 Cecil {-53.11 Hoey, 1-1I'Ie:' examined I.'II.'.111"'1'.eI;".= the the country ..'I.I:.11'..'I':-.' north.I'itII'tiI of n!" the '.i—1e Nzoia “ILItI'JE'. river :‘i't'et‘ lying13'121;
her-leer. Mount
between 11111111t Elgon 1":11I1'. and '.tItIIi the 111': Cherangani(heranpuni hills 11511. with 115111 aI.I. view 'ietI to 1.1 future11111111.“. European ILur'Igt-ean
.I-ettleIIIeIIt. The
settlement. The area area became heeattte known 1.11IL11I'I'11 as '.tI. the "Tt't'ttIII—HtItIia" and
the "Trans-Nzoia" 11111.1 was .I'ItthaeI—tlten'til.
I.I'ttIt subsequently
.III".1.I"I'1.‘__1.‘-'.1 and
surveyed £11111 divided 12.15.111.1131'1 into 11111.1 a:1 large 1aree number :1'.tt111:Iet' of 111' farm 1111111 plots p1t_I1-. many 111ttI1j.' of I.I'i’tieh were
1111 which Iwere taken Zak-.21
1.1.1 by
up h'- the the "Soldier "'.‘11111112'131‘ Settlement L:1ett11111111111. Scheme" hehente" of 111eI'Ie1ttt'Itttettt in
11.11:." Development
tIf' 1918. '.It the the region te:1111"1etf
I‘-.I;_.:ttI.-11 remained
5.11.111; until
slow until the the middle ttititi'te twenties, tI'eI. t..Ie.I~:. mainly 111'..'.111II_. on .I.-teetIttttt of
.I:1 account .II. the the long 11111:: transport tt‘t—‘tt‘iI-g‘Inrt haul 1111111 from 1".I31'
:‘:11111eI-_11;1.
'
railhead,
'
put in
'-
but ''-11 1926 1921.1
'
.he. Uasin
.
the 1._...1.II.11
. .'
(.:.-mu
Gishu
"
111111
-
and
'
httttle
" -.
Kitale I-eet.I.ItiI.
-.-.'
sections
-.-
I.II
of
-'
11-1:
1-.-
heII:I.I.-L:.I-.I.I.ti.-.
'"1
the Kenya-Uganda
.- '. . .- -'.

.'.‘11111'111' were
railway 'I'I'et'e opened I.Ipened to 21".11111: to
t-.I tratfic tn the ten-:1Itieiei'stehtr benefit
the considerable irII.':11'e:it of ttet'it'tt .II.I.I.1e in
III" agriculture 11': the the area. area.
1111: main
The 11111111 crops ITIt‘.'It1I.teeI;1 today
et‘ISIfC-III. produced tt_'.II.'11I.I.' are are maize, t'IIttiLIIe. wheat, I.I'ttttle-httrint. sisal,
I.I.'hea'._ wattle-bark, I.I1111'ee. sun-
.II':I-:'.11. coffee, I'I.I_'.11-
11eII.I.'et‘ seed
flower .I-eet1 and :1}. :‘et11'.'=.1111_ Dairying
11111.1 pyrethrum. Haiti-.111; and rearing; of
ttIIt1 rearing It'I.eI~tI.'.Ie1t for
:.I:" livestock I12:'1L.g11tifl' are
Z'I._I:‘ slaughter tt1-.I
'.tr-e also
11111113111111: activities.
important :1e111:".ie~'.
II-PREVIOUS “filth.
CEDLGGICAL WORK
li—PRIIWHHJS GEOLOGICAL
Reettrtia of
Records p.'eI.5-'..Iua geological
I.Ii' previous "I1'IIIe1'III1tttI11I1 made
getIlt'Ieiet'ti observations 111:1L1e in in 1.11131
this region regit1111 are are few. 1‘e11. .itIIteph
Joseph
'I'ht'imann crossed
Thomson ertIII-teti the .tt'et- in
the area T'I-IitII'eII11tIer.1I‘II
111 November, 1883 on tIr his '-.I.'a:.' from
1iI'. way 1~.;.-=:1'.IaIitt to
:‘r'I.I111 Kamasia Latte
te. Lake
K'iettI-ria via
Victoria Pitthet'aa in
I'ia Kaberas in the the Nzoia‘II..II.I:I.'. valley . 11.11.1111.
(Loftus, 1951, 11.151. pp. 60-61), anti
pp I."II._'I—1I'ItI. and .1a aimilaz'similar
'.‘ttIpettrIt to
.I'eIttte appears
route haI'e been
tI'.I have t'tI11tII-I-Ie-t1 by
heen followed 11:. E. 1-'.. E. 1-._\‘Iai1.er.
Walker, who I.I'htI noted IItItet'L that that the I11atet-I.
the plateau
reg-111111 west
region 11't of hi the I.I.Itearptttertt consisted
Eige'yt't escarpment
the Elgeyo etttit'e1:.' of
t't'IttItiz-tted entirely I.I!" lava,111111.111t and also tee-..'Ittiett'
a1:-.I'..I recorded
hanttett garnet
banded I.Inei-e-tea in
I.IaI'net gneisses in thethe (Nzoia 1".'“I.at'.Iia ?) t'iI-ez' 1"‘111'1111ter.
.11 river (Walker, 1903, iI-..II.'2I_1. p. p. 71. 7). PriorPrinr 11-1113.
(1903,
p. 239)
p. e~.itnet_ specimens
:91.described I.I.peein'tena of phetItIiite taken
I.It' phonolite 11.1.1211 from the Uasin
111131“. the Littain Gishu ptateau. attti
(.'.izI'IhI: plateau, and a
t'eII. years
few 1atet' Muff
:t'eat't. later 31111111111111.
(1908, p. p. 46) 411: noted t-tItet1 that that the E1pe:t't.1 escarpment
the Elgeyo e-..'a:'pn'ier_t revealed :eteale-J .1a
Iteetieitt 111.-
section overlain 1.1:.
gneiss t'IIer1ttitI
of gheitczt 'I'tI1ea111I'e rocks;
by volcanic rtIeitIt'. the ItIiettttie rocks
the volcanic rtIe1-tI1 were 111.11III112511113111}'
II'et'e subsequently
Ithptt'n
shown aI'. as an an upper
upper and and lower letter phonolitephentIlite in in aa aeetien
section by h:.-' Gregnr:
Gregory 11921.11. (1921, p. 108), II'II'II'II.
later repredueed by
later reproduced hirenket 111125.
1:11 Krenkel (1925, p. 3.111. Krenkel
p. 237). Krenket ail-31.1 also published published a'.I I.I:etIltIeieat geological
map of
map 1211 East erreneettaiy showing
Atriea erroneously
Ettat Africa I.IhnII't'ng the the Mount Mnunt Elgon Eignn volcanics I'tI1eanieIt as at eenttiguetn'.
contiguous
with the
I.I'ith the UasinUaain (.115htt Gishu 1211.:e lavas.
*References rI.I.IL'..IIte1.1
’Rt1tt.rt.I..I..:.are quoted on tI:1pI:-. 4:1 .'.IId
pp. 48 and 49.41-1.

.
 4.‘E

rete1ene 1: to
EErEeLT reference
Brief nLetLinLntphEe rocks
the metamorphic
he the Etgnn and
ELLEnnnL Elgon
hetLL-'een Mount
rnLkz-L between Lite-Lin
end Uasin
IEL'LEL'LhtL 'was
Gishu TTE'LELEE by
LL'LtL-L made [FEES-3. p.
h-ItttrLt-Hnghee (1933,
h}; Murray-Hughes 11. 2)2”: as part nt’
as part LEELenr-Lz-Linn
LL'EL'Eer discussion
of aL1 wider
LtnLLLetnEnL;I the
concerning the geological LneeeeLEnn of
eeeEngEeLLLE succession ef Western Kenya. and
ELL-Latent Kenya, and both T'L-EurrejLT-Hnghee
heth Murray-Hughes
L-.-':.. p.
1.1.1.1. cit.,
(op. [11. and
11. 6), SheLet-Lletnn (1951,
end Shackleton 11. 371),
11951. p. refer to
SEE]. refer geeEneL of
the geology
tn the nF the TLtntheeh
the Tambach
.Lee tEen of
section nt the the Elgeyo eEeLe to
eLee.t11n1ent. close
l-LEge Ln escarpment, the eastern
tL1 the margin of
eeL-Ltern margin eree.
the area.
nI the

Recognition LEE
ReeegnEtEe-n the farming
of the potential LEI
Fer nting 1.1L1tentELLE of the reL'fEen rL'tEnLnILLte-Lt
the region EntererLt E11
stimulated interest Eneel
in local
of .EeirtEEEL-zer
eenreee L1t'
sources fertilizer and and soil LL‘LLLLEL': the
set! study; LL'LLLL -.L'Lttwe
L'LreLL was
the area surveyed 'L-eLE for HLELELE‘CEEL of
tnt sources Ltgt':eLtEttLreE
nt' agricultural
lime 111' hen-"Lt
time by Scott (1932, 131. 11-.
IE'LEE-E. p. 2), and end the the red rent eeLt‘thrL
earths and hEeeE-t or
L—tL‘tLl black L1r grey clays L1.F
gLeL eELL1'5 of the L'L-tein
the Uasin
tjEitn LL-‘ere
Gishu deeerthed hjL'
were described .’L'EEtne (1936,
by Milne 11. 21E.
[ELLE-EFL. p. 21).
HLLEEELL‘LE EEEELEIFEL
Bullard (1936, p. 11. LEE-Ell: LLLELLEe _Lrt‘EL‘L'Et‘
502) made tLt‘L'LL-Lt:"et1.1e:1t'-L at
gravity measurements ELL
EL Kitale eLnLE
and Eldoret E'tE-E
EELELLt'eL' as
11L1Lrt L'1t' L' L gE'EEt‘L";t_L' LLa'e1L-'
part of a gravity survey of East Africa. LLF .ELLLt .-"Lt'rEeL't.

DL1LL'LL‘EpttLEItFL of
Descriptions the ge
LLE the L1.t1g:1L LLF
geology adjacent 'LtreLnL
of ndjeeent contained in
are eL'1LttL'LtL‘teLE
areas Ltt‘e in the tnlEnLL: 111g
the following
ELLLL1.L~L L1f
Reports of the {EeLLEng-EL‘ELE ..Lt.L1-L_L
the Geological Survey of KenjL-LL—EE‘Le Broderick
LEE Kenya-the FL'LE‘LL L'LtieEt.
BL‘L'ELEeL‘EeE-L Falls area, to tn the LLeL'Lt
the. west
(Gibson, 'IEL‘SLLL. the
1L1 L1LL111 1954), 1
[TherengL-Lnt Hills
Lhe Cherangani Hiéle area, LLreL-‘L. totn thethe north {_ELEEIIez'. 1956),
nerth (Miller, the
and the
E'lLJE-t’E't. and
Ext“: e1tI1Lt E.}ELEEL’EELL' L LLreLt. tL1 H e LL1:t:h
Kapsabet-Plateau area, to the south (Jennings, 1964). iI_LELnnEI'1g.:~'LL lEEt'E—E].

FtLLL'LentenL System
Basement -.-'.Lht1LL'n on
rneELL' shown
EEjL'L-Ltern rocks en the gCIEEt‘gECflE map
the geological 111L111 ofL15 the FLLEE-i-
LEE-rL1LterEL'L-LL Falls
the Broderick
:Lg'eLL are
area LEeL1L1:e-LE permeation
ere denoted eernLeetELLn gneisses gneEeeeL (Xs") t".31:’.1.""t and tttjgmetitee (Xg)
'LLLLLE migmatites 11L underunder the the same Lethe
.-'*L-:'.jL'tL'-ent. parts
e1._1!t_:1=.Lr. Adjacent
colour. pert-L- of LLLL1E111eE-L:=LTLE map
the geological
111E? the LteeL'111111LLn1-Eng the
thL-L11 accompanying the present :‘Lre
L'L':11L_1rt are
11: CII.‘t'[ report
LEEEE'eL'entEete-LE as
differentiated L'Lz-‘L. migmatite L-‘ttLL-en gneisses
L".‘L'._L_j-IL. augen
ntEen1LLLtEte (Xg), L'LnLE foliated
[Li-EELLL'LJ and
LLLLLLE-Leee (Xna) gentle or
tL1-ELL1tLtet'j granite L1?
111-.- rLLLLL1L1r1tL (1-),
granodiorite LEE-'1. under eeLeLtz'LL.
51111.11'1.11:Lr.e:e colours.
LtnLEeL appropriate

ELnekL shown
Rocks :LE‘t-Lir-L‘Ln in t"LLeL'L::1._-_L1Ltni Hills
the Cherangani
LIL the Ltt'L-e. as
'E-EEEELL: area 111L..t'LLL11EL'L‘-LLLE Basement
LL-L'. undifferentiated E:'L_L Lten:
EEL'EEL'E‘I'E'EEEEI System
1' .-L"t are
(X) eL1ttLL'.'.-L.Eent to
L-LL'e equivalent t.11.-L-LLLLL E’LeLL: (Xg)
tL1 migmatites t'let at LLt the 11L1LLELeL-“LL margin
the northern nLLLLLL-.1 of L1: the EELE-L-1LL t. area.
the Eldoret LLt'LL—L
At 1'. -"
I'TLL.t.LELILL1.L1-Lt.1
thin margin
.-"1.‘-. this '.-'
EtL'L-‘I 'tL’tLLLEL of
also horizons
'It. .'-1-- - -'-+'t1'
L.LI.LLttLL‘.1-t.1L _g!te.1.-.
1.1.- calcareous
.'-"- -1--"1"|-I' '"tL-

gneiss which I '

L'LE‘LILE“. do
-1.-'-
LLFE‘ELLL.
1-1..-t appear
LL.-L‘. not I':-
L1L1 the
on
"- 1"
I--L. -' ' 1- —-"'-" ' 1- "- '1.

1- 1E‘; -'-"-Lr ‘II‘I-".'1Ir'1-:_;1l'11'-I-E ----

' TH. LE. :1.
.1
L-
.11“- 1-

Cherangani
_..-L-LiJ-EbLLILFIE Hills E E.“1 map have
IEIL11L. been I_-L._.L..L-'| drawn
I._L..L;lL-"-IL to
[LEE the L.-'-_-'l-]:.LJ'-_-LI. boundary.
L '.'-L_- common
I- I"1.'I."1.r
{-11'=*-"'I"l‘ ' 1-1:]
FEE

[Il—PHTSIUG RAF! {‘1'

. III-PHYSIOGRAPHY

Tnnngrephy and
.1. Topography
1. DreELLeee
end Drainage
'l'ne erLLLL
The ret'erreLE to
area referred tL1 in111 this rrLLLL' be
L‘L1pL'.':L.t' may
:E1.::~.L report 1L divided Entn three
LELLEL'teL'I into 11*‘1 L--1eL_.1.hie units
tee physiographic 11:11:5-
L.L1|'_"LL=LE by
developed
fi: . '1 _..
tTL-Ltt..et1L-L of
LLEI‘L‘tE-"ELLTILLE influence
'[E‘tL-L- combined
EJjL- the E. 1— '_._:'-1 .
he LEE‘ -'L'.- LL'L'L. geology,
-L .E bedrock
. .._.l .
'e'LLtIE‘L— I‘L‘tL-LL LL‘ELLL‘I. 1;.
E’IJLLEL tL'Ltte earth-movements,
gL. 1113:}. Pleistocene —. 1"11 1.1

EILLFL' UFL THE} 111‘: : _. ._

andILLE
-_"L[-' erosion. They are:-
The Southern
E. The
1. hEEEe.
hEL'L'tLLtL hills.
.‘E-LL.Li'.ter:LtLCherangani
The Uasin
2. The
2. 1.1!L'LLeL'tLt.
CEEL‘LhL‘L plateau.
LE:LLE:1 Gishu
The Kitale
3. The enLE the
11E'L'LELt. and
ELI-Etttie plain, EELLLL'ELLnE and
NzeEe. Sosiani
t.1L Nzoia, -LL'L'.EL_-L.-'L.
Hipkert'en valleys.
:LLLLE Kipkarren ..1-

'1’ he Southern
The HEEL-EL. In the
CELL-'- ELLLLLLL' L' Hills.-In
.‘E'rz-nLLEEL-LL‘LL Cherangani L'L'L-rner of
LtLLtt]1..—eL-L:-.Lter-.1 corner
the north-eastern of thethe area -'-:L1=-1th—
the south-
L-‘LL‘ee the
EL1L'1thEElL-‘L of
ertt foothills
ern the CEternngenE
LEE the Cherangani rise nhrtt11tE1L' from
t‘Eee abruptly '"rLjn‘L-t the ]eveh: of
the levels the Nzoia :LL'
1:1EtLEE-ELLL1EL'L and TLEL‘LEheL‘L
LLE Moiben
L'L-LileL'LL to
valleys tn LLLLLLLLLLEL
summit heights -11'LeeeL-'EE1111 9,000
heEehtLL exceeding fee
E} _..IFtIFttE feet. ThEL n11]:L-Ln.Lt region
This upland consists nf
L'LegEn :1 ennetete ee'L'e.‘L-LE
O'f several
-
-LrelleEtridges
parallel EgeLL and and deep 1111LrLLLttt-1 L—eLEE
deep intervening valleys roughly north-south trend.
n‘L'rL.11.t1-1_.EL-1L-tt1rttenth
e_.L"-'L of trend. The The main main
E- li-te EEILEE'L‘S are
hill-features thnee of
LL-re those nE {.henLLLLnt-LLEE19.1418
Chemurokoi (9,548 feet), Kneettte (9,200
feet‘t. Kuserua 19.21.}l feet), KepsEEELtt
Eeet't. Kapsiliat
t'IEL5-E3.t1eet__..r
(8,539 feet), and LtnLE Kapserwa LT..:1-TL-1.tee:tL1hEe_h
1L111LLrLLLL (7,543 feet) which are er- grntthed
grouped to' tE e south
tL1 the enLE west
5-1.1:tth and eI the
LL'eLLt of th
KLEELLELtgttt-LLLE1L1t massif,
Kaisongul-Labot nteseit. ELaLLn
known locally EneeEEL e.as "Flat-top", stand Ltt
L'Lnd .LtLtrtL'E
EL-Lt— tL1-11”. and E1eEL1ht L1t'
at LLa height of LLhnttt
about
10,370 feet near
tt'ELB‘EEE feet near the rner eEn of
L'L'ntt'thern margin
the southern nI the the LhereneL-tni
Cherangani Hills HELL; area E95171].
{TLEEEIeL 1956).
L-LLeL- L (Miller,

{ELL-.LL'EL Gishu
TELL-.1 Uasin
The PEL'L-LeLLLL.—Thie is
GILL-I'LLL Plateau.-This E5 the exteneEL-‘e single
1.1.1.L.1et extensive
the most unit
11hLLEngrLL11hEeLLE unit
Lingle physiographical
the area
in the
in urea and and is EL solely determined by
.L'nEe11L-1 determined the111r
111' the eeLe nt limits
present nf the
IEnLEte of Li—lELEITI Gishu
Lhe Uasin phnnnhte
GESEIL‘L phonolite
The edges
ELLL-‘Lte. The
lavas. eLEUeLL' ofnt" the EeL-LL outcrops
the lava ere deeply
entern-pe are EneELLeLt by
etee 1111 incised the main
h}: the them and
1113E It rivers theEr
and their
trEhntLLrEeeL en
tributaries, so thatthat _prnnLEnent
prominent escarpments nLerLIL;ELLE-L the
eeeerpmente overlook Nae valley
the Nzoia in the
LLLEleL_L' in end
nnrth. and
the north,
Sneienl valley
the Sosiani
the En the
L-L-LEEeL- in LL-eLLt.
the west

~
 5

In the 1112 vicinity

3132131113 of 331 Eldoret
EJ31331'21 the 1132 plateau
3311121111 is 113 :113131'1;33:1113:113213-' ".1. 1131111 feet
1'232t above
111-33:33:31: sea-level;
11211—123321:
1
In approximately 7,200
it ptogt123-33313'32I3' t32133'131'3113
3133213 progressively
12 rises towards the 1112 Rift 33111313 at
111111 Valley :31 E13223.3
Elgeyo some :3: 131332 twenty 3131123 to
133' 3213133 miles 1132 12133.1.
11'3 the east
of 1".13133r32t. where
3.31" Eldoret, 3'13-21'2 :11 K113112112 it
at Kamorin 1211321125 an
1: reaches .'.-311 2.2":3112311
elevation of .'3t' just 23"3321'11111111'1
_1- 1.11 over 8,000 feet. 12321. The T1132
2113-253211t surface
present 511111122111? 11332 plateau
of the 3312121311 exhibits
32331111231113 a:1 downward
11313311331111": gradient
"1-3.31.1 t directed1111323213211 towards
13.133.313.215 the 1123': north-
111111121-
'325t. so
west, 3.1.3 that 21232113315; :31
111.11 elevations at the 313:31'111-3323313'2331 limits
11132 north-western 113111131 of 1113233111121111.
331: the plateau, for 1313111113213 near
1333' instance 11:111'
113323.':'. Bridge,
Hoey's 1131311312. :132 are roughly 1.111111 feet
133313.313... 3' 1,000 12:33 than
'22.: less 111.332 near
111:111 those "1.11.1121: the
1113231' Eldoret; 3.31:11112331 has
112-2 gradi.ent 1133.33
'1'-22:3 brought
been 1:12.311: both
':.'.31'33-'-13.3_.12‘-. about 133'2312:3221-113-2'111211113'111
2.2313111 by the present inclination of 13332 irregular
3.3.1' the 1: .3111 on
111 231'. 1.:11' floor 33132213 the
313:3 which 1332
1.13:1:3' were
lavas 3321': deposited 31231111311231 and 231111 by th12k2:11:13.3 of
31:33.3.23131332 thickening
133""a:1 progressive 131' the1132 phonolite .'33'22111111'.1:'311.'311~'3
32113331111112. accumulations
11333213133 their
towards 111-211‘ 5.31:11'122
source in 11132. Rift
111 the 33232313111.
'1.":111323' region.
131111. Valley
I'

.‘1'
'l' """"""

1
11"323'1‘113‘"

I
"I" '-."'1"' of 11‘."
" 3' the “1133131“ 3: 1'
The
—1"'TIL‘ comparatively flat
1'1321..‘: profile plateau is interrupted at Sergo it (7,870 feet)

...!"—
""3' " ‘1"2"-'13‘-"-
3_|.-.-1.] -.‘L_-....rl...lr3 1.-L|.....1._ 3.11 ...1... 1.3.- 2.11.. .“3 ...I3._..L.l. 3_LL .-.

:2"
.--

!:__,1

1'33
I";

Ir_'.
and 131111211211 (7,693
.-.I':3-1 Karuna 17.1315 feet), 122.13. where 33112232 inliers
'1. i:1.I-21':3 of :31 Basement 321223.332: and
513512.111 gneisses
12121532321211 System 13112:"..'.'1123
132111 quartzites
113323133311 the
11131112232132 through
protrude 1.13.11 flows
t'3132 lava 113.3333. and 3.1111131 above
11113.1 stand 1133.- level
11133332 the 331' the
1231-1 of 32331111t1'3'.
33:11'3'3111313111332 country.
1113:: surrounding

11.111" Kitale
The 1113111111." Plain 1"".3:3.'-.‘ and 3-1.::'.' :1.-1: Nzoia,
the .13-. 5:."
Sosiani 1.3.3::. Kipkarren
and 1'13..'-'-'...-"-:-.':'.-.' .1
Valleys.-The —11‘13- part _..'.1. . 3"1of
11.1:1.23-'.\3.’.-..13.'. lying
Trans-Nzoia 1_'3 .'.=1":1 within
3'3311:1.1 the 11-:- present
_.'I:.'.::..'.... area
.111... is 12:- undulating
LlI13.11-.11!-1-.'1-.'_ country
-..-...1.11-'.1_'. of 3.- moderate
.1132.--...-I;..-._1133 to 1.3.": low
13-1--
., ._'.2 ,-‘ .'2 _. __ '. _'.: ,. ' .3 . _. . .__. - _.' _.' .1. -... ,1. . .‘
-1111. Kitale
relief. 13.1.313- is 11. situated
:1.L..-..3-... at .11 the 113. north-western
.'.._1. 13.3.3121 I1 corner 3.33.113 ._ of ._.31 11.2 the area .1I.2.-1 at .1..1 an 2.1.1"3.33.I.1I.
elevation 3.11 of
'3." '- '. .. _ 3. . * ,. 1 ' .T ..' .1 ' -'-...1
1.21.111 feet;
6,200 132321- between
11321-31311 here 112132 2.1131 and Hoey's H3133.323 Bridge 1111113232 tributaries
1111311121133. of 331 the 1112 Nzoia -.\3.3'.L..1-3. river
1132111137.. have incised 11211:...-
-- .' . = ..
1.3.3.333:
broad 3:31-23.
valleys 123233.333.. 6,000
below 3-=.3. .31.?1.. .| feet,
t-22t. but 1
1233.1.. the
1.32 smoothly . - .. .......r...
:33'1'..33..3t-' ."1:_-. rounded :...
.-..3..:.3-.2--.1 interfluves 23..-, _ -.
1.1.2T11..l33.3-231.1121 stand at ..- '....._
.3. elevations
2.3.3.1...33 ;_._.
3

-
._ ' , -_ -_ _.. 3: '3
. .. ., ..', . . -'.- ...- . ..
. .1. . .- ..1 "- -.' .- .'
:31 between
of .'-2.-.3...-21' 6,100 13.13111 and .._1..1. 6,200 3.3.-3111 1.3.1 feet so 3....3..1.-_1I3.1.-.
that here there 132.2 is .3 .-.a widespread
3333.13.32.33. uniformity ..-.311.13.I.11_-. -.3-. of
-
t1;....-.—.-..2. corresponding
plain-level .-..1112:3I'.3.-33.1.3.:.1 to. ..3 113.3.
that at 1.3-2 the western33.3.2::-3-‘1‘]1 base :2-..:.3. of the -..32 Uasinl..33-..11 3.1.3.1.}.
Gishu phonolites.11.I-..3.1.31...33

1312:131-2-13'131133
Headstreams
.._-. _.
3'1
.'
of the 3.3.32 73.323311
.' _ '
Nzoia, notably ""'"'.""]"
-. .
.11-2.. Moiben
.
the 111-13232.11
."
..31.1
and (-123
_ "333-3332;.
Cherangai, .-.1-.-. 133.1233
follow 3332313
'_.3 . _.2
deep
_,

3I.:"..-..2-3:-:".12'3:3
strike-valleys incised 133213-22 13' in 1132
the 333311.22
softer '2.':2'. 333.2 .31'311313: 13211:;
metamorphic beds .31' of 11132-
the 3.:1'3111122212
southern {112211131111
Cherangani 13111:. hills.
13112211311121 2.7311121'31
Directional control of 1231' 1112. 31.2.31; pattern
the drainage 32:11-23“. by 133' the
13332 underlying
1;:":3.12.'131113.3 rocks 31321.33 1:: C3'111531112111..'1Li.3
is conspicuaus
.1' this
in 1131.3 part33:11'1 131'
of 13' 2132.1 13t
the area, but 1"1'11111'
further 13:3 to. 1132the 3332:3t.
west, near 11321'11 Kaisagat,
K131321g11t. :1132 the 531231111
Nzaia 13323311335 begins :1a
3'-.32:'3".2.-"1_3.' caurse
westerly 2111:1132 333.133.3113
raughly :11 1132.31- .3 1332.3 to.
at right-angles 13.1 1112 13231131122; strike
the regianal 3.3111132 of 1.1.1' the
11132. bedrock.
13231131332131. In 1:1 1111.3this
322112331.
section, 2232233333213:
extending to. .3 H.323":
Hoey's 11112;:Bridge .:'-..".1'.
and beyand,1323.122. 2:12 the river fallows 11111-23333 1112. the :'faat .'.-3.'..31 321'
of 211-2 the
I-3"2':1'3'.:'1'11—.l'.3213'.31 2-3'2'.'1:'3'..33':32I3t
narthward-facing escarpment .'at .-.'. 1133':
the 23.1322
edge af 11132 the UasinL':-.-3'1.'1 1.1113111
Gishu plateau, 13.:3.'.32.::3:. :11131
and 133 is 3'seldom
3211.3311
'
12133322 than
mare 11.13111 133.11
two. 3:1:2-2:
miles 111315.111:
distant fram 1133312.: the1132 northern
12.3:‘11'13'21'11 limits
11111:." of 111' the
111-.'. phanalite
32311331123113.2- autcrap.
-..'311".2.3‘3'331. 35.111132
Some
23213331:
seven miles 111:;-.'.': to.
131.113.
the west ":1 of
1'11 H33 3'.:3 '3 Bridge
Haey's 15.12.31... 1113.. :"\.3'.-..31.-1 takes
the Nzaia 1.1131213 .'.a 2332.3"?
sweep to. 13.1 the
.11.. 33.-11-11..
sauth, .1712: and
t.-:' follows
then 313:3 of. the
12-1.1.3..1 strike
.1'-.3. regianal
13.31.333.33 the ..1.....I3t133- '33 :1-. rocks
...-2 metamorphic .3"-.:.‘3 in
\. - 33.3L.-.1.—:'~3:31'.:.2-.—
'12.'.:...-...-. south-sauth-
-..1 .1a generally
2.3.3.2333
easterly ...-221.31
direction to. .13 Hemstead's
31211333....133 Bridge,
b..-3.12.‘3'.113'21'21'-
where it once 11:122. 2.2-1111
again takes 1.31.2.3 up 1. a westerly course
'11.}

31311
and 3313:1313
skirts :13: the 32131333131112
phanalite 32321131211122:
escarpment 1.3 ...'132. 3332-31
to the west 331 of F3:.'.33' -::1."13111.1 I'1'_3..3+1...1
Saysambu (6,340 132-211. feet).
' :. ...-L . . . .'... .' :..'.. '1....” .: . .1 3;.'_....-_. ..'.._-.
1- "'._‘ south-western
The .'311111112'31C2-1'::1. part
11211-12'1 .13.: .113-‘-'.
of the area is ..23 '._1-Ll-.li-‘l21
drained by .'_3 the
i1-3- Sasiani
"‘32'1‘3111111-11-21 13..-1:“..'3...1:.3.._-:'1 rivers.
and Kipkarren :I'-1.._ 2:.
1".'I2 Sasiani
The 1:133:11 :11 rises
:'1-3-2: near
3121:." the
.'.:1-2 crest
.1'-3:1: of
.'32' the
='."'.'. Elgeyo
1:1 12-3331 escarpment
32:2'..3:;.33..2. -. 13:13.1 and flows1. 33:: westward-. through
.'1. _.____....
1'1:.3-1-3'
1'1310121 to
Eldoret 521111:31133:__131;1112.1
13.1 Selby Falls (Blate I (a), 133.1.1'132.
Fig. 1), 33132132 it
11. where 13111213223 fram
:1 plunges 112313211312 edge .11
the 23132..- af the 11132.1Uasin 11.1311:-
1_}:::1'I11 phanolite
Gishu 11'1321:1I1I.1I311112 rocks,
1111123 metamarphic
311311113131112 anta 1333:1333. and 13311333331 the
11:12-21 follaws
1133.11 then 1.1.1: 211'
1112 faat af the lava 91323133-
1122 1:13-21 escarp-
:11-231: to
ment '.-..3 11:11:30.
Turbo, 232111211113
eventually 12313111132
jaining 111-2 '1\'1p13;:£11'1'3211 river
the Kipkarren 1'13'21' near
112:3: the 111-2 western
3332531221: margin 311:3:32111'. of .11' the113-2
.'31'3'.-:-..
area. T112 The K1111-31133'223.
Kipkarren 113.321 over
river .3332: most
332-2331 311'af 1::
its 23.31.1121:-
caurse 333 strongly
is 3:11'..'.3.'.-2.13' influenced
11311:.323'3-2'323-1 by 133' the 1"13-2 narth-
:1.-3111'—
3123132313 . 3:12:3111 133.1 11332 11331.112'1' 53.312121 11121331. 131111 13.3 11:2 3.3.1.321111-3'332.-3t .'..31' '1 31112331 11132 I'13.32*
westerly grain af the Basement System rocks, and to the south-west of Turbo the river
31:1:3' exploited
has 23132312311211 a'.1 tectonic
1221111112 zone 11311132 in
111 which
331113.211 fissile
1113331132 mylonites
11131323111121; have 11:132. been 1.13.221 preferentially
31212122111121133' eroded. 32123113211.

.‘31:3I:1 drainage
Main
3
111'.1II..33.--.- systems
' '-.
..-.:t2-. ... in
1--
.3. the
__
31:3. area
.312. are
.-.:-. shown
:1.3333..1 in
.--3
.1. Fig.
1:31. 1.
..
_'.-..'..1. .._. _-...-.-.-. .'.._ _'.- 1

1113313111311 Surfaces
2. Erosion Surfaces
—I-—'I.'1" 1 'l - 3. .- - . I... - -3.. 1
1._._—\ ,.____.., .13.?1 1.
1‘12.

—- 'I—J'
111 the
-.'—[‘2' area:-
.11'33-12—
.l-.-.--

Three erasian surfaces

1.3.-'-...'.. ._'.LI—f‘: can
LlL’bl‘hll!
32.1. 3.2131 be recognized
13..-3.33-2-1.‘ in 3'3.
|"3.'

1..-

1. T112
The K1121: 11113111 131111
Kitale plain and 1.71.3133
Uasin 1.3111111
Gishu .51113—3'2:3232:.::i2
sub-volcanic :3.I:'1':12-2
surface 11.11331.1—32'
6,100-6,800 3..".3"1."11'1 1233.31-
feet.
.. T132
2. 21131— C121: 13232131111 (?)
The end-Cretaceous (":11 surface
133 111'. 113232 7,100-7,800
‘ZijtIjLT; 33111.1 feet.
12-21.
-. 1121217213111: .31' 113.32 1-3211131. 11111132221 '1111111'32321.
.I-J

3. Remnants of the Lelan .plateau 9,600 feet.

T1333 Kitale
The 11:11:31.3: Plain
P1131131 and
31333.1 3’.-'
Uasin311'1'11 Gishu
13131113 Sub-Volcanic
.'5'.13".3—I-'"3313131312 Surface.-The
.S:3.3'_."..'cf'3'-'. -'.l 1332 lawermast
12333211112312 lavas 1:13:13. of
231'
1332 Uasin
the 1.1311113 (1235311
Gishu 3331;112:111
plateau 32:31. rest on 1.333. 13233311311211113'
sparadically 311111111111132d
distributed tuffaceaus t1311'1132223113 32311313323113
sediments 111331 and
agg123111321'ut323 which
agglamerates 33111211 lie
1132 uncanformably
113132323111'311'11113'1313' on3311 a11 peneplained
12211233113113232 surface
33113111232 of 131'."-.3:'t:11313'-31']:31113'2
metamarphic rocks. 333321333

iI
 -
6

' “t DIN
FTP-we
_.- “I L‘- .' H... . .- 1. _ f1_".':II v _ ' A: r. l_.. r Fcr—f" _ _ e'.-' bar‘s-Ms.
..__ CI: .. _..I I Iu'”|5
. __ =
[LSEEUID‘ -
*" main - -. T a a h. s t—LH_- - a- E I]i 'a .’ _ .- . . {fife {wee-a
s ' 7".
’2 . set-3' ., "a
- ' -
- t“ , at?”
_, ,5, . I.: :ITI-FHLIEC-KCII
,. ,
.- I , _ @5‘- Emil
.— .1 -:.:~,
I._ I. ?'._:
---‘?~ ........ - - '- ' I
'-.-_ “HF ':-I.' .- r."-I'I|-'- '3' I'll .-- n I ',
3:3. _1.-".'|! JiF'ICEIC-i

I :5” : fr" am' .

.-' "l":.'.f-
,h
= - 1"}!
se II
a1-
.1 I.
.' .’. 34'.-1'“ I f I?)

-
._ _. I I _.-

, e- sf:
..
,
s._.
f ,
' _ '._.
d—kaesLm-i
_- |
- ;_- as fish
I" r". '::

"H. a}. 4'.. _

r-1:“I— "N. 1L _._.- p. ' I.h_ _.
"'
. =-
I:was .- _
V1
'4
3]:-
'-
"s "-’i .=:.':-.‘.'-.-.—" “‘1 5. Ti
.- _ ‘ " I

-
- .'-r‘ a". -. -
_
" ' u’J-IJ‘V r3; f."
I' I

- :1 £3 r' r
_ '"I'I _I _j
I! "\- _ I— _~.__ _ .- _.
'— -' _ s,- s—'
“flu-IF ’._r ._ — I.I -..__ I:
' .- | --i__ -.
1. _ _
‘rI: .LI "2' . .-
“i". ' . _-_._—.—._
-~.. - 55C !.
n' f ' I
t-I! J"I ."1 i

- 1.3;"
I 1: I—1l | L—.
.UASIN GISHU .

/ I."
-~..rs. a: __ -

Pt.
h 'r __ u
PLATEAU -
I I5 I F..':I.It__. 1-..— 1'

-
"(=1
K~~~~;t;:
.- I
I I -I_:'_'
I
, -! 119?. I:
lAKE
' "I _“I :5 2.51:.'| |

V\
1% — {in . I

_ .J". Ill—1-
L--
~ -(6700) ~RGOlr
I _
.-" '."I '
--:-(67501 --.. (7130) "'''''0
5-1:. SERGOIT
= E_ ESP.
' Ir+ ' _ _
.L.'1 -.._ '\\ -:
T.-- II (7870)' I

~
. 11
. I‘I‘s. ' I I
I 'II '- _
I' '-.h '——
.' "I2.-
"---
:.-I '1.

. —. I
. ..
-' i. \' -(7100)
\
'1
III.
u.J

I
I
'"
I.

..,
pH:
-:_:

—-._
I
'"
; -u":
-i_
-~—.-...__‘ ru. : ..,
5r:
5...!— —— -" -. I: "' (-‘-
—'
J —
a- n' 1-11"
.-. _
SCALE 3 u "u'
O'30'N
10 "-‘.I
15 MILES
J

~ Remnants of lelon pl2!teau

~—=-: '-'._"’U ESTEI’C-F"=E!'TF. I-Wafglnfifi Cur

_-_=-.£-'. Computed
/;;, 7543'
Escarpments
begnts In
Cements-:1: heights treat
.I" feet
alt-.95 IFIC'WEI'!
(margins of lav2!flows}

E3 Remnants of the End-Cretaceous (l)

~ . surf2!ce - Il-i'-Z""'
6200' E..:]-i_'-:.":"5I_T_-trI-:
Barometric EE--:T:T_-I“E5gi".!5 r": feet
spot-heights In FIE'E‘E

he:gh1s of
EEIIFT‘EI'E'i'I heights
- (6700/ Estimated sub-lave
ed" sub-lava
. Katale surface .
r-,:::, --IKitale surface sIJriee-e in
surface that
In feet

seetzens A-B,C-D
For sections
For r 2:. 2E
see Fig.
A ELK-IT." see

Fig. I-Physiographical
Fig. 1-?t siegraphieal map
map of
Hi the
the EIrIIIl’E’I 21W"-
Eldoret area.

Eles'atiehs of
Elevations ef this seb—seleaaie planation
eater-isis-‘e sub-volcanic
this extensive eah be
piaaatieri can determiner] with
be determined aeedraes
ssith accuracy
airing the
along eseatpreeiits of
imi'th-t'aeihg escarpments
the north-facing at" the Where the
plateau where
the plateau stiriaee is
the surface is accessible an
in an
aeeessibie in
east—west section
east-west same thirty
seetien some miles in
thirty miles length. and
in length, in the
and in western escarpments
the western the
where the
esearpaiehts where
base of
base the lava
ei the can be
lava can traeed in
be traced tierth-sduth section
in aa north-south treat Hoey's
seetieri from Bridge to
flees-"s Bridge Eideret.
te Eldoret.
data on
Additienal data
Additional en the height of
the height at the sub-veieahie surface
the sub-volcanic is available
stiri'aee is here—hides
treat bore-holes
as-"ai ahie from
thrdugh the
reaehieg ,through
reaching plateau lavas
the plateau the metamorphic
itite the
Eas'as into basement.
metamtirphie basement.

base of
The base
The at the phehehte is
the phonolite hieated at
is located elevatidri of
art elevation
at an fijflfl feet
ef 6,200 the
at the
feet at earth—
north-
ss'esterri eatreritit}? ef the piateath near flees-"s Bridge, and rises
western extremity of the plareau, near Hoey's Bridge, and rises southwards to setitha-ards ten heariy
nearly
6,400 west of
[eet west
p.400 feet rif Eldoret. steeper gradient
Elderet. A‘I steeper displayed by
is displayed
gradierit is by ,the east—west
the east-west seeder]
section

~
 T
11:115'L'1:11 Ho~y's~
between 11111:}:‘5 Bridge1311111511: and11111.1 Moiben
111111111111. where
1111.:1'1: the
1111: surface
5LLt1I'LLL'L: slopes
5111111115 upwards
11p'-L1L'11."L1~'1 towards
11111111115 the :11:
51311111111111
sQUthern C'.111:r:111g:1t11
Cherangani hills 1::115 11111;!
and 1111: 51111111.L11:t' 1:11
the shoulder of 1111-: the Rift Rift‘1Valley .at :11 2‘1128 feet feet per 1111‘ mile.
:1111L'.
I111: north-westward
The 111.11111- 15':5111111111 projection
11111j1':1':111.111 of
1:11 this
11115 surface
5111LLLL is 1.5 .concordant
LL1nLL11L-L1111 with 151111 ,the
1111-: 1:11.5'
eastern LL11‘ 11- sub-Elgon
151111—1-I11L1..111
5L111111L:: and
swface 111111 1111:
the KitaleK1151: plain.1:.-111111. The1111': 5L111—t'.1_:1:111
sub-Elgon surface 5"L111L-'11:: rises 115:5 gradually
:r'L1L1‘L111i:_L from 1":1111 111111111
about 5,3OQ 11.51111
11:1:1 'near
feet L'L-L1111‘ the
the Kenya-Uganda
Kc1131'211L'gL111L111 border harder to 111 5.11.1111
5,600 feet 1IL'L-L:t 1111112611
fifteen miles 11111L11'5 further
1'=_11"-.}'11:1' to 111 the 1111: east;
1:551. .1a
I'LLL'L1’1L11
further 1L111 ten 1111111111
miles 1211515111115
eastwards ,the 1111: L'1'1Ltr11111L1
extreme 1111:51-:11'1
western 111111: limit L11 of the 1111: Vasin
L'.1.5.311 111151111
Gishu phonolite 1111111111111:
515111.111 11:
stands at a11 base131111.11: level
11:11.11 of1111 5,800
5.511111 11:11:11
feet :11151:
close 1111155111.
outside the 1111: western
1L1LL15‘LL' 1'11 margin
111.111.1113 of 111' the1111: Eldoret
I-IIL1L.1'.'L1'.
1111:11.
area, 51: so that 111111: 1111:.
the 5111:1— 1711:113111 111111
sub-Elgon 1.1115111 £11511L15L111111:1:5
and Vasin Gishu surfaces 5111111“ share 11a 1:11111111L1L'1
common peneplain 1:1:11':L'1L1111 11111111.t
having
1155113111 311111173
1111:1131 westerly
a*1 mean slope of 111 21.521-- feet1913? per (1 :: 245)
1111.1: 11
171121” mile over a'.1 1115::11.L'L1
"‘L-1:'.11.-L".." distance of .1 11:111'1'15EI1‘L1LL1'1'--.
..1.-:' approximately
65 miles.

111 the
In 1111.: 1111111112111
northern L111L1 and western111:5111'1'11 1:5LL'L11‘_1.‘1111L'1115
escarpments 11f of 111L1 1111;111:1111 11.111111111151115
the plateau tuffaceous 51:L111111:111.5
sediments with 1.15111
11115511 wood,
fossil 1511011. and and green1:112:11 agglomeratic
11§g111111u1'11111:111115 11111111111111}; nephelinite
tuffs containing 111:1:1111'31111111: fragments
ft‘11g11111:115 accompanied
11L:L'1:It111:11:1"L'L1
1'11; pyroclastic
by 5111115111511: biotite, 111111111: melanite,111L"1:111111:. and111111 perovskite,
1111151151111: 11.: 51:51:11 beneath
are located 11:11:11.1?1 the 1111.1 base
11:15:. of 1:11 the1J1:
111111111513 at
phonolite :11 Moiben
111.111.1131 :111L1
and Selby 51:11:1117111151511131:
Falls, where the ‘11-'11: deposits
1113;113:5115 51:1L11'1:t1
seldom :‘5-.::-:L1'
exceed :11 20 feet11:1:1 init: total
‘LL'1:'.-.-§
1h1:kn:55. Immediately
thickness. 1111n'11:1111111:11' outside 1.1u15iL1L the 1111:. eastern
1:11.51L:1'11 boundary
1111111111111 of 151‘ the
1.1: area;
51:11. near'1-L-111' Tambach,
1111111111131. over 1.'.'1L"'
511111 feet
400 1'L11:1 111‘
of 1511111111111 1|:11:'11:1:11L1.15' 51:1”.11111LI115
stratified tuffaceous sediments 1:511 can be 111': 51:11:11
seen in 111 the.
the face 111111: L‘1-I
of the11:1: Elgeyo
1:112:15'11 1:.5'L'Ltl'11-
escarp-
11111111 beneath
ment 11:11::111 phonolite
15111111111111: 131111121111211111.
(Shackleton, 1951, 11.151. p. ]:1. 3TH.
371). The T111: T31111.11L'.-'1
Tambach beds 1111:1111 L'1'1t11:11'.
contain a
31111::111: fauna
Miocene 111111111 1I'including
L1L";I_11:1'I:11L1r crocodile,
11111112111111: tortoise
1111111115: :111L1 131555111115 a11 rhinocerid,
and possibly 1111:1L1L::11-L1. 111111 and like 111-11: the-'.I'1L'
111111111:t' sub-volcanic
thinner 5LLb-1-1‘11L'1111LL: sediments
5LL'j1-L111:1115 observed
111:5:11' :11 to 111 the
1211: west, 11112.51. 1:1'111111111 11211112511111: 111:1'1'5'1:L":
contain nephelinite derived from 1111:15"
1::11'111 511-1113111111:
early Miocene 11111111115115.
eruptions. These T111115: beds 1111115 were
1111111.: 11111111511111
deposited in 111 local
11:11:11] depressions
11111113551115 11111.1 over 1111 an
1L".1."11'L111 surface
erosion 1111111111115 in
111111111111.1:h1:L maturity
51-111Lh approached
5t:t1111:1.1 which 1::1111' Miocene
111 early 11:11:15: 111111
5111;151:111: times; they were 115'c 51.11111
soon
1111 1:115 1111:1315 covered
afterwards 1:115:15: .1111 by floods1.1111115 of L11 phonolite
11111111111111: from11:11:11 the 1111: Rift
11111111Valley
'1111125' region.
1": L11. 111.

5111;11:1111:11'111 (op.
Shackleton 111...". dt., p. 1:. 3T1-11.1':L'L.11L1111:1:L1
379), recognized the 1111: coincidence
1:51311L1'11L'111:L-: between
1.1:1'L'L1L'L'1L the ‘11-'11: Uasin
1...'L1.51'L1 1.115
Gishu
5uL'IIL1'LL1L1. the
surface, 1111:111:111:11:
eastern 1'11 sub-Elgonsurface,
51.111- 1311:1111 .15'LL'1‘1111'L'1:.L and
11111.1 ,the
111: Kitale
K1151: plain, 11111111. stating
51:11:15: that 111111 together
1L1g1:11111.'1‘ they 111:1
1'1:}1r1:51:1111:1'.1 1111
represented 1:111:11511111 of
an extension 1:11 the1111': sub-Miocene
SL111-I'1'1113C13I'113 bevel 11:11:} having
1111111115.: a:1 westward
'51'1:15t'L1L11‘1.1 1111 tilt of 111‘ approx-
1111-1111111:—
1111:111:i1.' 1
imately 1 :: 3311
230 1'T1Ct‘LL11111.
(Trendall, 1959, 11.1511. p. 1:L—1'1.
4). T111:
The Kitale K1111]: 11111111
plain 11:11.1.had, 1111111151111.
however, been 1111:: regarded
1'Eg111'L1:L1
1111' Dixey
by [115:5 (1948, 111'115'511'. p. 1:1. 26)
2111 L15 as LLa separate
5:11:11'1111: surface
51111171111: residual
11:5111111'11 L111 on the 1111: Uganda
LIL .111LL-L'1 or :11 511b—7‘1111.1L1L"'1Lr
sub-Miocene
11:11:11.111'11'11. T1115
peneplain. This 51:15 view 11115 511p1111=r1LL1 by
was supported 1'1}: (111151.111
Gibson 111.1551. (1954, p. _r1. 9)
“51L who
1.5-}1L1 found
t'L.1.'-.1:1L1 L1'1'11JL1nL::
evidence 111' of a
IL'LL::-1] change
local 1111111151: in 111 level
11:11.:1 at 111 the
1111': base
1111.51: ofL11 the1111:. Elgon
Elgnn volcanics,
1111:11111'L'5'. and 111111 11.-1:11-
drew -.-.'.'LL::1.11'L111
attention to to the 1:1:
1:111:51L1c1'111111: ver,tical
considerable 51:11:11'111111111 of
'5-'1::rtiL'111 separation 1.1111111} feet
L'1f 1,900 111:.1'1-11:L'11 the
11:1:1 between K1151: plain
1111: Kitale 11.11111 and 11111.1 the 1111: West11:51
111111511115 lying
l111121: lowlands
Suk 151111;: at 11:11:11 of
1111: foot
:11 the L11 the L15L'11111n'11:111. The
Tt:.1115—"'5'11111;'1 escarpment.
1111: Trans-Nzoia '11:: existenceL'1Li511:11.L'L" of 111-:
1:111" the
1511:1311 plain
Kitale 171111111 as :15 a11 separate 11:1'L1'L is
1:111:511111 bevel
51:51:111111: erosion 1.5 also LL'L'L'L'L:.:L"1'_1 by
111511 accepted 131111-1115 (1960,
"115' Pulfrey 111.1111]. p. [1. 7) T1 who .'1.!1LL'-
r- .
11111155 that
stafes 11011111 of
111:11 south 1511111: it
111" Kitale .11 is 1111: surface
1.5 the 11:11:11 the
L111 which
5=L1L"1'L-1L:1:. on 111‘1'1'15 of
111': lavas 1.11 the Eldoret 1.1.11L11T11‘L'1 region.
1:11:51".
11 :11: laiddoWTI.
were 11111.1 L111'5111.

111: old
The GM land 11111111 surface
5:111:1L: underlying
underlying the 1111: volcanic
151111111111: rocks
1111:1115 north
:1111111 of 111' Eldoret
1-I11.'I.L11'1:1 is 1.1.1 irregular.
1111:5111L11'.
L111: at
and 11: the
:11:- time
11111: of 111' the
12111: first
111.51 Miocene
31131::11: lava 111111 extrusions
11511115115115 it 1: was
11:15 evidently
:1'1L1:111I1.' immature,
i:'1'.'11'.11:.111:. isolated
151.11:-111:1.'
“:5111111115 of
residuals L‘1f the 11111111111111111111: rocks
1‘5515111111 metamorphic
11111111: resistant
1111: more 1111:1115 being 111-:1' it.
.51'L'11'Lt1:rL1L1 over
1'1:n scattered 31. T11: 5111.111:
The smaller
11.i]15 were
hills pmbably ultimately
151:1: probably 11111111511115 1:111'L11Ld
covered by 1215' 5111:L1:..55115':
successive lava 111511 1111111115.
floods, but 1111: 11.5 1:51.11: 1.11
as 'a.1 result of
511h5eq111:11tt:rL151'1111.
subsequent erosion, they 11111111111111
11‘1-1."‘_1' have again 111 111.1111:
aJppeared 15 small
111-:111 1'as inliers L11.
5:111:11] 1111111115 of 3.1:155 standing 1111111
gneiss 511111111111g only
_.u

1—

a'.1 few
11:11; feet11:1:1 LLL.
above11111: the
11111. present
DI‘L.51:111 5111111115:
surface of 1'11 1111: 51.111011111111155" p1111111111::5L
the surrounding phonolites, :as. _-'_:.15 1:1111
can be 1.11:.11:11:11
seen in 111
11:1 area
an. 1111.111 of 5111.11.11: miles
51:1'111'111 square
111" several m111:5 between. L1:.51:111 and
L'1: 11:11:11. Leseru 55:15 Bridge.
111111 Ne!i's "1'11: ~arger
133111115111. The 1'1111'LLL'1:
11111L1'L'11 inlier at
EL'rgoitL standing
Sergoit, 111111111111111
5.11111111111:1 more than 600 fLL11L1111111131111121111.
111111 feet above the plateau, was 111115511111 never
15:15 possibly 11:1L-L11'L'L1'51111L1L'1
covered by 111.
1. '1'
lava.
111.1951. . .

1:1:1.'-L-'1:'§L:1115 on
131151115] elevations
Original L111 the 5111'1'1-‘1LrL1L'L1'111'15t
T111111L1:111: sur~ace,
1111: Miocene whilst conspicuous 1111111111.:11'1L'11
1:1'.11151:11-L:1_.'L.1115 topographically,-
were 51:11 .51:
1.11.1.1: not 11111101111111. as
so important -.:5 111-55111:
negative irregularities, 5.'1Lh as
11'1':1:111'111111:5L such 11:11LL551L1115 ._.'11:1
115 depressions 5111:1515. 11'111Lh
and 1valleys, which
5:115':L'1 as
served 111L115 of
:15 areas 11:11L111'15'
L'1LL'1111'LL11LL11L111 for
1111‘ accumulation eady Miocene 5L L111t11:11t:1111111 and
31111::11: sedimentation 1:11111L1111LL1 the
-11111 controlled 111L
local LleLLiLm of
1L11'::'11 direction 111L115-'1:1111:111 111.
L11 movement of the 1111111 1211:1155.
111:. lava..flows. .

T1551 end-Cretaceous
The 511-1d.1f.'r51m1:1111115- Surface.-To
.1111'111LLL—T1‘1 theth: west15:51 of 111 Sagotio
511511211111 151111
and C11:t‘11111'1:11~:1‘.1i
Chemurokoi 111:
the
Cherangani hills
5151111111111 Cherangani
southern p1:51:nt aa remarkable
11111.5 present 1111 summit
111111L1111'1115' .of'
11111151111111.1111 un.ifortnity height5.
51111111111 heights. F1_1-1'
For
severa[ 11: the
111i11:5 to
5115:1111 miles 111111111 1111'
the north of Kapserwa 11:14.11 11:11:11
K511511115: (7,543 1111: 111111111131
feet) the country is 15 deeply 11111151111.
deeply incised, 111.11
but

..
 8

erests of
crests ef the interfluyes an
hilly interfluves
the hHly stand at
all stand at between Tfiilfl feet
between 7,500 and 7,600
feet and feet; this
ESDD feet; eresiert
this erosion
surfaee stands
surface aheut 1,000
stands wbout higher .than
feet higher
LOUD feet the sub-Miocene
than the peneplain. it
sub—Mieeene peneplain, been
has been
it has
referred to
referred as the
te as end-Ciretaeeetts surface
the end-Cretaceous and can
surfaee and be. correlated
ean tbe with an
eerrelated with leyel
eresien level
an erosion
seen in
seen in the summits of
the summits the Nandi
ef the highlands south
Nan li highQands ef the
seuth of Naeia (Gibson,
the Nzoia 1954. p.
tGibsen. 1954, 9]
p. 9)
and in
and the Kisii
in the seme 100
highlands some
Kisii higMands lUU mi:les further south
miles further [Shaekletea 1944,
seuth (Shackleton, p- 13,
1944. p. and
13., and
1946.p.52}
1946, p. 52).

Sergeit Rock
Sergoit the hills
and the
Reel: and seen seuth
hills seen south of Turbe: ineluding
ef Turbo, including Kaptabei hidalat.
and Nda~at,
Kaptabei and
residuals of
are residuals
are ef the reduetien in
surfaee; aa reduction
end-Cretaeeeus surface;
the end-Cretaceous summit. elevations
in summit the
ef the
eleyatiens of
residuals frem 7,870
residuals from feet at
TEETH feet at Sergoit Reel; to
Sergeit Rock feet at.
120d feet
te 7,200 Hdalat is
at Nda~at espressien of
an expression
is an ef
the inelinatien ef
westerly inclination
the westedy of the end-[‘Tretaeeeus surface
the end-Cretaceous tn the
parallel to
surfaee parallel sub-lylieeene
lesser sub-Miocene
the lower
surfaee as
surface shewn in
as shown 2.
Fig. 2.
in Fig.

Henri-rants of
Remnants ef thethe Lelon the north-eastern
Pft'i‘ft‘ttl'li'.-- in the
Listen Plateau.-In eerner of
nerth-eastern corner ef the regien the
the region the
highest. parts ef the seuthern Cherangani hills reaeh eleyatiens
highest parts of the southern Cherangani hills reach elevations of between 9,000 feet ef between ilflt'ltl feet
and 9,600
and and are
feet. and
{9:600 feet eeneerdant with
are concordant with aa high eresien surface
high erosion referred to
stirfaee referred as the
te as Lelen
the Lellon
plateau [ls-tiller. 15156. p. 5]: whieh estends te the nerth
plateau {Miner, 1956, p. 5), which extends to the north outside the boundaries of the eutside the beuntlaries ef the
present area.
present This is
area. This the highest
is the and oldest
highest and reeegnized in
peneplain recognized
eldest. peneplain in the {Theran—
seuthern Cheran-
the southern
altheugh further
gani. although
gani, further to nerth aa higher
the north
tn the eerrespending to
plateau corresponding
higher plateau prineipal
the principal
te the
summits of
summits the Cherangani
ef the massif has
|Iii'hei'artgani massif has been {up cU.,
reeerded (op.
been recorded 3].
p. 5).
gin. p.

fl..-_5L;s—ist.-tay er
IV-SUMMARY eeeLeey
OF GEOLOGY

The geology
The ef the
geelegy of area is
the area determined by
is determined twe rock
by two greups the
reel-t groups ef
eenselidatiens of
the. consolidations
were separated
whieh were
which by a
separated ,by seat period
a vast earth history.
ef earth
peried of are : ——
They are:-
histery. They

]. Metamorphic
1. reeks of
Metamerphie rocks the Basement
ef the System.
Basement System.

3. Tertiary
2. layas anti
Tertiary lavas and tufts.
tuffs.

System reelts
Basement System
Basement rocks forming Cherangani hills
southern Cherangani
the. seuthern
ferming the bins eensist.
consist of ef Pre—
Pre-
para—gneisses and
eambrian para-gneisses
cambrian ef originally
sehists of
anti schists erigin and
sedimentary origin
eriginaliy sedimentary aeeempanieti
are accompanied
and are
by crystaUine
by limestenes and
erystalline llimestones quartaites. The
and quartzites. The rocks threwn into
are thrown
reeks are inte feids eyertttrned
foilds overturned
tewards the
towards west so
the west that the
se that sueeessinn is
the succession repeated across
is repeated the strike;
aeress the beth foliation
strike; both anti
feliatien and
shear-planes dip
shear-planes tewartis the
dip towards east.
the east.

In the western
In the half ef
western haM the area
of the and granodiorites
migmatites and
area migmatites feunt'ia-
eenstitute aa founda-
granetiierites constitute
tien te
tion to the
the metamorphosed sedimentary rocks
metamerphesed sedimentary seen in
reelts seen in the The feundatien
north-east. The
the nerth-east. foundation
traye—rsed by
is traversed
is easterly dipping
by easterly eentaining metasomatized
thrust—aenes containing
dipping thrust-zones mylenites.
metasematiaed myilonites.
lntrusiens of
Intrusions ef metadolerite peridetite are
and peridotite
metadelerite and feund in
are found in the area.
migmatite area.
the migmatite

Tertiary pheneiite
Tertiary lat-'as entered
phonolite lavas entered the regien from
the region the east
frem the and seuth—east
east anti during the
south-east during the
lytieeene period.
Miocene They obscure
peried. They pertien of
large portion
ebseure aa large the Basement
ef the System and
Basement System their
reaeh their
and reach
greatest thickness
greatest in the
thieltness in herderirig the
eeuntry bordering
high country
the high the Rift Valley near
Rift VaHey Twe
Eigeye. Two
near Blgeyo.
separate flows
separate haye ,been
fiews have distinguished in
been distinguished in the Uasin Gishu;
the Uasin the lowermost
Gishu; the rests on
lewermest rests en
sediments in
tutfaeeeus sediments
tuffaceous in the Sesiani vamey,
the Sosiani west of
yalley. west Elderet, and
ef Eldoret, alse near
and a~so and
h-teiben. and
near Moiben,
extends to
extends Turbe and
te Turbo Heey‘s Bridge.
and Hoey's it is
Bridge. It eyerlain by
is overlain similar and
by aa similar less extensive
and less flflw
Efilflnsiwe flow
between Sergeit and El
between Sergoit and Eldoret. de ret.

Late Tertiary and

Late Tertiary and Pleistocene faults eenneeted
Pleisteeene faults with rift
connected with s-‘alley meyements
rift valley dispiaee
movements displace
heth Basement
both System and
Easement System phenelites in
anti phonolites the east
in the and north-east
east and part of
nerth-east part area.
the area.
ef the

- ~---
. .
 A
LWwsw.
5 W. B '<
EN.E.
E:RNZOIA
MEDIA I-IL':-F'f'5
HOEY'S BRIE-mBRIDGE NZOIA Ii. :M‘HJ H'v'r'f-
KAPSERWA I2'CHEMUROKOI
I if Pr‘ |.,JFEI.',‘J ' i',,'II FEET
|I I . I I
'I'ZI'ZHIIFI
10000 - 'I I I I
~id l Elfin - Plateau - - -
10000
|I
I I - - L --1el2.n .J'.1~~a!!...
9000 I I
I I III/”f h'"'-.. .. _ ___,H'HHI Eran“- mic-c:
9000
I _ I -- . . _- --._.
nflcru
8000 - I I E-.-JC|
.8000
_ . -I .;;..-I:.-Ir_~t.3u'_er:u._.,~. BIIr‘lEl'H‘.
Surface ___ .-
I l . .. - _E'2i-~@S.e~s2-
UASIN GISHU PLATEAU :nflfl

""1
11D
7000

EA.” . —— —'
.6000
I
I
I K,tale
K: “JP
*a______———
Surface
flurfaEP-— -|—f—‘=U-’
-———-
I LEI-AI}. k4 [:.a PH“

:rr.:.'—.r ' : l : :1 rTI-r'r-r: :.m

P ._ nT L34. L.‘

W.._..-r_-..____ __-r .k I ,_
'--
I
I

_..»:"
/ I— _ — —-' _
I III.-"_'

Eml“
- .._ 2~e- --.5l!.d.a~
_'-I-..____---"lr
:;:::
.3--'.'l.-=“-'-5 - -
7000
h
l- I;-::c.".-.'
6000.
BEBE
5000 '- .- ___ _ __ __ _ -_ .-_____._... . .-_ .:.-GLI-
5000

-
-
<; WSW
W 3': W E N E —D
ENE-D
HF MPIAHI:
KAPTABEl QR SEISIM.
SOSIANI ..EIJEH...
lESERU. BERGEN]
SERGOIT mama,
KARUNA I
FEET I l, FEET
EET \D
Il hL‘Jfi-lfll II
NDAlAT i I I
I I I I I' I tau-:.';-
- 9000
9000
Il Il '.l 1| lI I
J
II-:Ir.1'
800.0 J II ., 'I L- 'I |I I. ml.I;.I-ex.=I:'In-:--.:I-III7'
End-Cretaceous? 'I'J-J'l-‘F
Surface'3‘ I — . ._- E'J'Jn
8000
End-Crmacnum
End-Cretaceous? " I' Surface
“Id-=55” .. II .-"""'a "I --»-—'—"T '_'_'-F
.7000 lI

~=~t~~
TUBE I "lII-IIIHMI‘ |.' _ --"'”""-II I Ila" I '_ _ . I I _ I I . -.- .l'_l L_LJ l | LIP-”II!“ “I?" —IE|__:|__|_I_I 5r-1'lil— T1--1-L'l:fl:l—r --.[:l . -:-', _.': '_',1 7000
_ Mic"?

.
IILtd E g" 5’" l. - I H11rrIr1-n._ _ImflIl'l'l'TTlJJJTWTTTL'.lTEEIJ'JTE'E—‘l-‘1'-'--'"-"mrr'trz-lHl-Llld-ll""l'—l—'—l""l " " " 41-45] ‘
bUlill-‘t_____.
6000 ~a~~~r~~~~--
___ ___ ---— ' — —- --' , ' II I ._ :5:I|':I:
6000
ETJEIII
5000 ___ _ _ _ fl _ ENC-1' 3' .
5000'
-
-
. STALL
SCALE .
0U, 5I, .10,I} In, MILES
1SMIlES
VerticalscaLe= 44 .x1- l'l::1'-turl:a-
‘."'I.=Irtlca| scale Horizontalscale :.Lale
-
.1 I ' i Ulnper F.lr'|fl""|i'_}l|'l!.-."': lLlll _ E l ner phnnmlltm
, 1::.':-,.',,1 Upper phonol,les Lower phonolites
Far lJ'IE'E.
For lines It)"
01 mmmru
section III-BIC
A-B,C-DD ear;
see Fig
Fig, 1l
Fig. 2--Sections
Fig. 2—Hccti0ns to
ti) slmw Hue. Erosion
show the III-ruminn Surfaces
Hurfucm in
in the
“It: Eldoret
lflldnret arm.
area.
 ll}
10

1t—DETr'ttlLS OF
V-DETAILS GEULUGY
GE GEOLOGY

l. The Basement
1. System
Basement System

The group
The term "Basement
grcnp tenn Systern“ is
”Easement System" is applied Kenya to
in Kenya
applied in i'eci’ss
inctainnrphie rocks
te metamorphic
crystalline timeshares, sehists, gneisses and granulites, with attendant.
including crysta'l1ine limestones, schists, gneisses and granulites, with attendant migma- ntfgnta-
including
tites, and pegmatites
antphibelitcs and
lites, amphibolites haye achieyed
which have
pcgntatites which achieved their present eentpesitien
their present composition as as aa
result ef
resuU of recrystaiJ!lization and ntetasnniatisnt ct sedimentary
recrystallisatien and metasomatism of sedimentary rocks. reett's.

Basement System
The Basement
The einhraees alt
System embraces all the reeks in
ntetatnerphtc rocks
knewn metamorphic
the known Kenya
in Kenya
excluding the
excluding sediments and
the sediments cf. the
layas of
and lavas Kay-irendian and
the Kavirondian and Nyanzian which
systems, which
Hyanaian systems,
tegether 1with granite intrusiens eecupy a crunparatiyely srnall arc: in
together with granite intrusions occupy a comparatively small area in the Nyanza region the Nyana’a regien
elf western
of Kenya. Migmatites
western Kenya. metamerphesed sediments
and metamorphosed
ls-tiginatites and seen in
sediments seen in the area.
Elderei area
the Eldoret
are, therefere. arneng seme cf the thirst westerly espesed Basement
are, therefore, among some of the most westerly exposed Basement System rocks in the System rec-ks in the
territcry, and
territory, and as might; ,be
as might be expected, significant. structural
display significant
expected, display pctregraphic
and petrographic
structural and
features dictated
features by their
dictated by They can
pesitien. They
regienal position.
their regional can 'be diyided into
he divided distinctive
three. distinctive
inte three
grtiittps : -
groups: —

Ntigntatites, granodiorites
til} Migmatites,
(1) and amphibolites
granedierites and the. Turbo
et' the
antphihelites of area.
lathe area.

Zenes of
[2} Zones
(2) cataclasite. mylonite
cf catac1asite, phyllenite in
and phyHonite
nu-Ienite and i1}.
in (1).

_"~.-1eti.ininrphesed sedimentary
{"3} Metamorphosed
(3) yelcanie rocks
and volcanic
sedimentary and the Cherangani
ef the
reel-Ls of hills.
l[Liter-tutgani hills.

1. i‘t-figittrtrirer, Granodiorites
l. Migmatites, and Amphibolites
{iiF't'i‘l'lt'..3-:"Jri'lr'i'.t‘.'."it"'.".' and r'_i_.r' the
A it] pliihril ire-1r of Tirrhri Area,
ri'ie Turbo hit}: 2.
.ilrtirr, with r.. -_
Z wit-1s of
2. Zones 1'

.‘L-tyienire
tf'r'iraelasirc. Mylonite and Phyllonite
Cataclasite, and Pityilriirire

Migmatites granodiorites dentinate

and granedierites
Ts-"ligmatites and dominate the geeiegy of
the geology western half
the. western
ef the half of the.
cf the
area, which
area, cempared to
which compared the Cherangani
re the uplands is
{Therangani uplands is ef lew relief.
of low Utttcrnps are.
relief. Outcrops et'ten
are often
smeethly eroded
smoothly platfernts or
eredcd platforms jeinted "tors"
well jointed
er well with no
"ttirs" with suggestien of
he suggestion stratiticatien
ef stratification
of the rcchs-
cf the rocks, as seen in
is seen
as is in the Eherangani regien.
the Cherangani region. The reeks are
The rocks cearsely crystalline
are coarsely crystamne and and
rnassiyc; they ccntain abundant. pegniatites anti ettartrnyeins
massive; they contain a:bundant pegmatites and quartz-veins and are often invaded by and are eften ins-acted hy
TypicaHy the
delerites. 'l‘ypieally
dolerites. the migmatites are. grey,
rnigrnatites are with aa pink
grey, with dappling or
pint; dappling streaking due
er streaking due teto
cencentratiens of
concentrations cf microc1ine; feliatien or
mierecline: foliation ilnw-lan'tinatien is
er flow-lamination indistinct. and
is indistinct yariahle in
and variruble in
directien and
direction dark 'biotitic
and dark inclusiens are
hintitic inC'lusions eeinntetr In
are common. parts of
setne parts
ln some til the netah-ly
area, notably
the area,
areund Hemstead's
around Bridge and
flcmstead's Bridge senth of
and south Turhe. the
et‘ Turbo, inigtnatites are
the migmatites eeinparatis'ely
iecaliy comparatively
are locatly
hen'tcgcnccus and
homogeneous and grade
grade into granedierite and
gneissese granodiorite
inte gneissose mere. rarely
and more granite.
rarely granite.

cnntaining mylonitic
Thrust-zenes containing
Thrust-zones gneisses and
mylenitic gneisses trayerse the
phyilenites traverse
and phy~lonites. granitic
the granitic
and have
inundatien and
foundation preyided avenues
haye provided late-kinematic petash metasomatism.
fer ilate-kinematicpotash
as'enucs for t'lwing
nietasentatisnt. Owing
tn the
to adyanced migmatization
the advanced the rocks
cf the
tnigtnatiaatien of censequent obliteration
and consequent
reel-ts and reccgniaahle
et recognizable
ehliteratien of
sedimentary features
sedimentary is net
it is
features it not possible te deduce
pessihie to suecessien.
deduce aa succession.

3. Metamorphosed
3. R’rielts e)“
Sit-striatedrnry Rocks,
Herrtittrirpltrisrid' Sedimentary the Cherangani
of the Hills
C..'r"ierriir_i,-"-riiri Hills
well-ditlerentiated series
is. weH-differentiated
A para—gneisses and
et' para-gneisses
series of eecupies the
schists occupies
and schists nerth-eastern
the north-eastern
cerner of
corner the area,
ef the and is
area, and eeincident in
reughly coincident
is roughly in extent with the
estent with Cherangani
senthern Cherangani
the southern
hills which
hiHs rise sharply
which rise trern the
sharply from leyels of
the kvels the Kitale
cf the plain and
Kitale plain upper Nzoia
and upper saltey.
Naeia valley.
quartzites and
Massiyc quartzites
Massive litnestenes are
crystalline. limestones
thin crysta~line
and thin interstratified with
are interstratified hietite—,
with biotite-,
garnet- and
graphite, garnet-
graphite-, sehists representing
kyanite-hearing schists
and kyanite~bearing claystencs or
fen-her claystones
representing former shales.
:33- shales.
Interbedded calc—silicate granulites
lnterhedded calc-silicate gneisses deyelepcd
and gneisses
granulites and frent rnarls er calcareeus
developed from marls or calcareous
and massive
sandstenes, and
sandstones, para-granulites and
euartz-felspar para-granulites
massiye quartz-felspar deriyed from
para-gneisses derived
and para-gneisses fren-i
the recrystallisatien and
the recrystallization metasematism er"
and metasomatism' sandstenes, cernpletes
of sandstones, completes the rnetanierphie
the metamorphic
assemblage.
assemblage.

:""" .....
 'I
I

l l
11

The reelL'Ls have

the rpcks stratiferm disposition,
a su.atifomi
ha'L'e a with uniform
diseesitien. with te the east;
tlip tO,the
tiniierm dip east; shaj'p eentaets
sharp contacts
are often
are seen between
eiten seen ene rock
het11'ee.n one type and
reel: type its neighbour
and its the. sueeessien.
in the
neighhettr in and etttereps
succession,'and outcrops
ef the
of fissile members
mere fissi'le
the more resemhle normal,
sttperiieially' resemBle
111e111i1er1. superficiallJIy flaggg sedimentary
nermal, flaggy reeks.
sedimentary rocks.
e'samintien ,both
("leser examintion
Closer heth of strttetttres in
et structures in the field ane‘
the field testere and
and texture eee1e1'1sitien ef
and composition reeks
of rocks
in thin sections
in thin 111.111'e1'er. that
if-enteastrateL however,
seetiens demonstrate, eriginai sediments
the original
that the sediments have reer'jL'sta'L-
'eeen recrystal-
hare been
itee'L and
lized transfermeri by
eften transformed
and often by the gren'th of
the growth minerals that
new minerals
ef new that formed expense
at the expense
termed at,the
ef the
of initial elast'ie
the initial clastic grains and 'by
grains and hy the intrethietien of
the introduction ether constituents,
ef other neta'el-' petash
eenstitttents. nota:blypotash
and
and, seela.
soda., --- - ,- -.------
intlL'LeLLee L117
the influence
L'ntier the
Under of moderate temperatures and
meeei'ate temperatures and high pressures these
eenhnfng pressures
high confining these
rocks have yielded
rL'L'LL'i1'Ls have yielded by shearing anti
L1_1L-' .1L'he1'1ringr and plastic L e11L'.i'11
eiastie flow. sente eases
In some cases newly formed minerals.
newly termed minerals,
11artie-Lilar131' the
particularly mieas, have
the. micas, have. grewn
grown in dynamiea. lg impressed
the dynamicanJly
111 the shear-11.1:1nes 1111
i111presset'i shear-planes that
so that
their erientatirm is
their orientation is 11et11eeessarily
not, necessarily related related to heeding.
eriginal 'bedding.
11. original

The apparent 1-11L-Let'

H11: 'L'tt‘J‘u'J'Ltt'ei’tl 1.11 sLleeesaLL‘lf‘l
order of succession seen 1.1 the
111:1:1’1 in the southern itzlLs is
Catlin-£11111] hiUs
111L1_L-L]11LtL-1 Cherangani L-Ls.
11. as
ft‘fllfl‘fl-H.’ -' '-
follows:
fl ppl'r'f_1_1'_
Approx.
11”“.1111111'-1.1
thickness
(feet)
{Wilsjr't'I

Bietite—hernhienee gneisses
Biotite-hornblende gneisses . . . . L . . . . . L . . . 1 .01?{l— 1,200
1,000- l.21.".1t"1

Hear [sites
Quartzites . . . . . . . . . . . . . . . . . EUG— 1,OPO
200- liltltl
-
|QuartrL'.'1—t"e1s1.1athie para-gneisses
Quartzo-fe1spathic para—gneisses and
anti biotite
hietite para-gneisses
pai'a—gztezsses 1.1.i1h 11111'
with thin
h1etite1l11_1r11hle111'le para—gneisses
biotite-hornblende para-gneisses.L .L ..
. L ..
. . ..
. L ... . - .. .. "1,000-
L Llltill - BLI'L'H'LlI'LS-
3,000
HUl'IlblCl‘tdE-d1.035idfleflflltC-Sph'flflfl:"t'l'LLE‘L'l
Hornblende-diopside-epidote-sphe~e -g1'L'-L1.L11ites and
para-granulites anti para-gneisses..
1'11rL1gt1eissesL. 2.01.10— 3,000
2,000- 11.011113

[-13.111111'L-L'-gar11et sehi
Kyanite-garnet sts. kyanite-sillimanite
schists, 11~L-';LL11ite silli111a11it: 1LLL1Lst1 eietite—garnet sehists.
schists, biotite-garnet schists,
hietite 111tisee'1'ite sehist
biotite-muscovife s. graphite
schists, graphite sehists
schists' . . - ..
'- .-.', . . ... .::.:
. . . .
--~'." Eitllt'i— 1.21.111
'''30{}-'-1 ;200

Qtiartaites
Quartzites . . . . . . . . . . . . . . . L . .ti'Jtl—
300- 61:11.1
600

1L’L'Llit1artzt'1-l‘els1_natl'1.i-e para-gneisses
Quartzo-felspathic 111-: 11-1 1111.L~Ls s and
11111.1 biotite
hietite para-gneisses
para—gneisses with
with thin
thin
hietite1heri1'nlenele p
biotite-hornblende eara- gneisse.
ara-gneisses. . .. .. .. .. ... . .. " ..L . . . 2.400- 3.00111
2,400- 3,000

Hornblende-diopside-epidote-sphene para—grrantth tes and

Hernhlende— tliepsitie— epidete —seh1e11e para-granulites 11L11a-g11e1111e1
and para-gneisses,
garnet amehihelites
. garnet-amphibolites . L . . . . L . . . . . . . 3.1'.'1tlt'.'.}— 4,000
3,000- 11.0011

hg'anite-garnet schists,
Kyanite-garnet sehists. kyanite-sillimanite
its-'anite—sillimanite schists,
sehists. biotite-garnet
h1L11111L- 1'1ri1et schists,
sehists.
hietite-111esee'L-1te sehists.
biotite-muscovite schists, graphite
graphite sehists
schists . . . . . . . . 3111'}
300-- Silt)
500

Qtiartzites
Quartzites L . . . . . . . . . . . L . . . . . 3110—
300- 5011"?
500

thiartae-t elseathie para-gneisses

Quartzo-felspathic p.111 1L —g1eisse and hietite para-gneisses
and biotite para-gneisses with
with thin
thin
'L1ietite-her11hle11rie para-gneisse
biotite-hornblende 1.s, garnet—amphihelites
para-gneisses, garnet-amphibolites .... .. . . IOLUOD—IELUDD
10,000-12,000
T111111.
TOTAL . . . . . . . . . . . . MEGS—30.000
20,800-30,000
-1_.-

The
The majer
major units
up.its are repeated in
are repeated in aa number
humber ef
of felds
folds that
that are
are es-ertttrned
ovetiurned tee-ards
tow~rds the
the
west.
w~st.
The eentrasting
The features ef
contrasting features the Cherangani
of the C-herangani meta-sedimentary
theta-sedimentary seettenee
sequence and the
and the
migrhatites and
migmatites granedierites 11f
and granodiorites the Terhe
of the Turbo area are summarized
area are summarized in Table II.
ih Table II.

IF
 ,-

1'}
12
.-'

II.—t‘.nt-:Taasnt-tn FEATURES
TsaLu II.-CoNTRASTING
TABLE nF THE
Pennants OF Senistawra OF
Marsstnarnnssn SEDIMENTS
THE METAMORPHOSED THE
nr THE
HILLS AND
Casasnnsm HILLS
CHERANGANI THE MIGMATITES
sen THE Gassnntnatrss OF
sun GRANODIORITES
Minstsrtras AND rue
nr- THE
Tnaan Antes
TuRBO AREA

i Cherangani Metatnnrphnsed
Cherangani Metamorphosed
FEATL-‘as
FEATURE !5 _ Sediments
Sediments Turbo Migntatites
Turhn Migmatites
(Superineumbent)
(Superincumbent) {Fnundatinn}
(Foundation)

tnpngraphy, high
Ribbed topography,
Ribbed relief
high relief Flat or
: Flat undulating country,
nr undulating lnw
enuntry, low
. relief
relief

Alternating hard
Alternating and soft
hard and beds
snft. beds Cntnnaratiyely uniform
Comparatively hedrnek
unit'nrnt bedrock
Tnannaaruy
TOPOGRAPHY that strnnglyint‘iuenm
that strongly influence the drain-
the drain- that nnly weakly
that only the
influences the
weakly influences
pattern
age pattern
age drainage pattern
drainage pattern

Good eapnsures
Gnnd exposures Poor tn moderate
T’nnr to eapnsures
ntnderate exposures

Stratifnrnt, flaggy,
Stratiform, difi‘erentia-
well differentia-
llaggy, well Massiye coarse-grained
Massive hetern-
enarse-grained hetero-
: ted tnetasediinents
ted metasediments - genenus migmatites
geneous finw-i‘nliated,
migrnatites flow-foliated,
Quartaites, limestones
Quartzites, eale-silieate
lintestnnes calc-silicate with abundant. amphibolite
with abundant and
atnphihnlite and
lcyanite-granhite
para-gneisses, kyanite-graphite
para-gneisses, i hintitesenfrsren
biotite schlieren
sehists, psammitic
schists, para-granu-
nsantn‘ti'tie para-granu- ; Some areas of
Snine areas nl‘ more unit'nrnt
rnnre uniform
lites
lites [ aennlithie
xenolithic granndinrite
granodiorite and
and
PETannnaaHy
PETROGRAPHY - granite
granite
Pegrnatites rare,
Pegmatites enn-
thin con-
nnly thin
rare, only Pegmatites ennnntnn. both
F'egn'iatites common, ernss-
hnth cross-
cordant yeins
enrdant veins cutting ennenrdant
and concordant
eutting and

felspathiaatinn
Albite felspathization
Albite Potash pnrphyrnhlastesis
Pntash porphyroblastesis

No reenrded
dnlerites recorded
Nn dolerites Dolerite dykes
Dnlerite dykes

Major rninnr folds

and minor
Majnr and nyerturned E No
fnlds overturned deeipherahle major
Hn decipherable fnlds
ntajnr folds
tnwards west
towards west

Regular axial-plane
Regular nften
inliatinn, often
axial-plane foliation, Foliation steep and
dips steep
Fnliatinn dips yariahle
and variable
ennenrdant with
concordant bedding; dips
with bedding; dips
3tT‘—5t)" E. or
30°-50° HE.
nr NE.

Static-Tuna
STRUCTURE Cnnintnn reduction
Common int-'erted
nf inverted
reduetinn of Aeutenlastie
Acute defnrntatinn
plastic deformation
inlds
limbs in folds
limbs Easterly dipping
Easterly thrust faults
dipping thrust re—
faults re-
lated to
lated t‘nlding in
tn folding superin-
in superin-
eurnhent Cherangani
cumbent series
l‘Cherangani series

Thin rnylnnitized thrust—annes

Thin mylonitized near
thrust-zones near
base
base

hires-tt'rit‘es, GRANODIORITE
(1] MIGMATITES,
(1) awn AMPHIBOLITES
G_a.-t?-;nntnairr; AND THE-L TURBO
n1: THE
Asiattiuntttes OF Antes
Tuaen AREA

In the
In parts of
western parts
the western nf the area Basement
the area System rocks
Basement System ate best
rnelts are espnsed in
best exposed the
in the
Hania valley
Nzoia Snysanahu, in
arnund Soysambu,
t-‘alley around the Sergoit,
in the Snsiani and
.fergnit, Sosiani Kinkarren valleys
and Kipkarren the-
tn the
yalleys to
snuth of
south Tartan, and
nf Turbo, in the
and in Haptahehhidalat hills.
the Kaptabei-Ndalat in these
hills. In reginns, and
these regions, adjacent
nyer adjacent
and over
areas of
areas ni many miles, massive
square miles,
n‘tany square hedrnek is
granitie bedrock
enarse—grained granitic
ntassiye coarse-grained enntparatiyely
is comparatively
unifnrnt in
uniform in composition, there are
and there
enrnnnsitinn. and layers each
meta-sedimentary layers
nn meta-sedimentary
are no pnssessing
eaeh possessing
ntineralngieal and
distinet mineralogical
distinct features as
textural features
and textural the Cherangani
in the
as in hills.
Cherangani hills.

-. ....
 13
13

Dutcreps present
Outcrops present aa heterogeneous
heteregenceus appearance
appearance imparted
imparted by by numerous
numereus pegmatite
pegmatite
ycins
veins and
and dark bietitic inclusiens
dark biotitic inclusions in
in aa grey
grey er pink gneissi
or pink l-Lisaminatien et
gneiss. Examination of thin
thin :cctiens
sections
taken from
taken frem specimens
specimens cellcctcd eyer aa wide
collected over wide area
area tend te show,
tend to shew, however,
heweyer, that
that the bulk
the bulk:
eempesitien
composition and testtire is
and texture is in
in fact mere uniferm
fact more uniform than the mixed
than the inised appearance
appearance ef of the
the
reeks weuid
rocks would suggesti
suggest.
On the map
On the map accempanying this report
accompanying this repert areas
areas ef
of cemparatiycly hemegeneeus grane—
comparatively homogeneous grano-
dierite have
diorite haye been
been diflierentiatcd frem neighbeuring
differentiated from yeined granedieritie
neighbouring veined migmatitcs,
granodioritic migmatites,
altheugh
although thethe dirferences
differences between the two
between the twe are
are slight
slight and
and centacts
contacts are transitienal.
are transitional.

frii Migmatites
(a) .irfigiiirr tires
The migmatites
The migmatites censist
consist elf three cempenents:—
of three components: -
{ii
(i) IGrey
Grey er
or pink
pink cearse.
coarse, yeincd micrecline gneiss.
veined microcline gneiss.
iii}
(ii) Pegmatite
Pegmatite y'eins.
veins, quarts. lenses anti
quartz lenses and stringers.
stringers.
t’iiil Bietite-hern blende inclusions
(iii) Biotite-hornblende inclusiens with
with senelithic
xenolithic to te agmatitic
agmatitic habit.
habit.
Granedieritic
Granodioritic gneisses
gneisses censtitttte
constitute eyer
over Elli
90 per
per cent
cent efof the migmatite areas.
the migmatite areas. in
In
hand—specimen the
hand-specimen the grey
grey parts
parts censist
consist ofef quartz,
quarts. plagioclase
plagieclase and
and biotite,
bietitc, and
and are
are
intimately veined
intimately ycined by
by aa rclatiyely
relatively cearse. pink, microcline-quartz
coarse, pink, micrecline—quartz combination,
cembinatien, which
which
seems to
seems te have
hay-e formed
termed by by the
the penetration
pcnetratien anti hsatien ef
and fixation petash throughout
of potash threugheut the fabric
the fabric
ef
of the reel: se
the rock so that. there. is
that there is an uititnate tendency
an ultimate tewards uniformity
tendency towards unifermity et'
of cempesitien.
composition.
Pegmatitic veins
Pegmatitic ycins eften
often parallel
parallel the
the weakly
weakly defined feliatien ef
defined foliation of the
the gncisses. The
gneisses. The
pegmatitc yeins
pegmatite veins are knetted with
are knotted large porphyroblasts
with large perphyreblasts efof micreclineperthit
microcline-perthite e and
and mat—
mar-
gined by
gined by thin
thin bietite-rich
biotite-rich sclyages: semc ef
selvages; some the larger
of the larger pegmatites
pegmatites cut
cut acress beth the
across both the
cencerdant
concordant pegmatites
pegmatites and the feliatien
and the foliation ef
of the
the cnclesing
enclosing gneiss.
gneiss. Quartz
Quartz stringers
stringers and
and
lenses are
lenses are rare,
rare, but
but may
may bebe seen in some
seen in seme outcrops.
eutcreps.
Dark
Dark bietitic
biotitic and hernblcndic inclttsiens
and hornblendic inclusions yarying
varying in in size
size frt'irn
from thin
thin elengatcd
elongated strips
strips
er
or schiiereii
schlieren tote large
largc blecl-ts
blocks measuring
measuring manymany feet
feet acress
across are are censpicueus
conspicuous in the migma-
in the migma-
tites.
tites. These
These bietite-rich
biotite-rich reeks
rocks are
are eften
often seen
seen asas angular
angular brcccias
breccias representing
representing the
the dis-
dis-
rupted parts
rupted parts ef larger biotitic
af larger hietitie erar hernhlendic
harnblendic masses.
masses, the the fragments
fragments af ef which
which have
haye.
been ferced
been farced apart:
apart by by the
the interyening
intervening gnciss {Plate IV,
gneiss (Plate i‘y’. h}.
b). In
In seme
some espesurcs
exposures the frag-
the frag-
ments are
ments are seen
seen as curyed plates,
as curved plates and
and in many instances
in many instances they preseryc an
they preserve an internal
internal felia—
falia-
tien
tian erar banding
banding unrelated
unrelated tn to the
the dew feliatien ef
flaw faliation af the
the ncighbeuring migmatitc.
neighbauring migmatite.
Thin sectiens
Thin sectians taken
taken fretn
fram aa large
large number
number af ef specimens
specimens celiected
ca]]ected eyer aver aa wide.
wide area
area
shew that
shaw that the
the migmatites
migmatitcs are are afef manatanaus
meneteneus compasitian.
cempesitien. The tcsture is
The texture perphyre-
is .porphyra-
blastic. due
blastic due to'te the
the grt'iyyth
grawth ei."af albitc—eligeclase
albite-aligaclase er micrecline
ar micra perphyreblasts in
cline parphyrablasts in aa granu—
granu-
litiaed and
litized and cry-'stalleblastic niesaic af
crystallablastic mosaic et quartz,
euartai oligaclase,
eligeclasc. and and microcline.
micrecline. A A raugh
reugh falia-
felia-
Lien is
tian is aften
eften imparted
imparted by by lenticular
lenticuiar aggregates
aggregates ef quarts shawing
of quartz shewing advanced
adyanced distartian
distertien
and
and strain,
strain, inin centrast re the
contrast to' later farmed
the later fermed felspar
feispar parphyroblasts.
perphyreblasts. Biotite,liietite, accempanied
accampanied
eften by
aften by accessery
accessary iraniren are,
ere, apatite,
apatite, sphene and! er epidete.
sphene and/ar eccurs in
epidate, accurs in small
small ragged
ragged
flakes weakly
flakes weakly arientated
erientated in in the
the finer-grained
finer—grained partions
pertiens et‘ the matrix.
of the matris.
The dark
The dark calour
celeur ofef inclusians
inclusiens in in the
the migmatite
migmatite is is rellated
reiated te the amaunt
to' the amettnt of et" contained
centained
bietite and
biatite and to'tn the
the presence
presence ef hernhlcndc which
af harnblende which is is net
nat cemmenly
cammanly faund feund in in the best
the hast
gnciss apart
gneiss, apart frem lecal areas
fram lacal areas ef af ceniaminatien
cantaminatian near near to' te inclusiens.
inclusians. Dccasienally
Occasianally the the
hietite ar
biatite er harnblende
hernblende is is accampanied
accempanied by by diapside,
diepsidc. sphene,
sphene- and and ilmenite,
ilmcnite. So' se that the
that the
incltisiens themsciycs
inclusions themselves may represent aa late
may represent late stage
stage in the dissolution
in the disselutien et af calcareeus
calcareaus sedi~
sedi-
ntcnt.
ment.
{it} Granodiorites
(b) Cii'ttnrirfiei'iirs
The granedieritcs are yery cleseiy
The granodiarites are very clasely related related to'te the granedieritic migmatites,
the granadiaritic migmatites, and and aa
distinctien
distinctian between
between thethe twe is based
twO' is based enan appearance
appearance in in the field rather
the field rather than
than en pctre—
an petro-
graphic
graphic differences
differences determincd
determined in in the laberatery. These
the labaratory. These granedierities
granadiarities de dO' net pesscss
not possess
the typical
the testures exhibited
typical textures eshibited byby granedierites eccurring in
granadiarites accurring in anan undaubted
undetibtcd intrusive
intrusiye
setting. far
setting, fer instance
instance inin stecits and ring
stacks and ring dykes
dyltcs inin valcanic
yelcanic regians;
rcgiens: thus
thus the
the felspars
fclspars are
are
rarely euhedral
rarely euhedral er internally aened,
ar internally zaned, and
and micrecline
microcline is is mare
mere abundant
abundant than
than ertheclase.
arthaclase.

.
 14

0 I 2
~ .L ,mm

(-11)
(a) (b)
(b) ('1')
(c)
j—Ihan'ings of
1111.1. 3-Drawings
- Fig. 111' thin 1111111111111 of
thin sections 1111.11.11 from
111' rocks the western
111.1111 the 111111 of
11151111111111 part 11.11l111'1'i
the Eldoret
[11 the
111-1:11:—
area ;-
1_11_}[§1‘1111111liurile
(a) Granodiorite migmatite. Specimen. 34/665,
1111311111151: Specimen 111.1111. at
.‘1-11111111111 river,
314-11115. Sosiani T511111.
111 Turbo.
nie11111. X 13.
11211111111211 nicols,
Crossed {1111111111. (Q),
[.1. Quartz 1111:1111'line (M),
{1}}. Microcline 1'_"I.Ir_. Orthoclase {II-'11.
[711111111e11111e (0),
I’l11gi11eh111e (P).
Plagioclase 1P1.
{I1_1."—|Lem1lith
(b) Xenolith in mignmliie. Specimen
in migmatite. fiperimen 34/699, 34'6991 from[1111111 Kipkarren Bridge.
Hipl-Iflr'ren Bridge.
{11111111111131 light,
Ordinary lighi, X {ll-11111111. and
i3. Quartz
.1: 13. {111"}, Hornblende
ffllfifl'fll‘ (QF),
111111 felspar [HZ].
H1111111len11e (H),
1.]inp1i1ie (D).
Diopside 1111.
Garnet amphibolite.
11.1] Garnet
(c) Hpeeimen 34/672
:1I1111hil111111e. Specimen fr11111 Ndalat.
34.11172- from 111111111111.
711111111111. Ordinary
.
light, X
light, IS. Quartz
Sir-1'- 13. 111111 felspar
{31111111111 and Hurnblende (H),
[QF]. Hornblende
{eh-[1:11 (QF), [13}.
Garnet (G).
{H11 Gamet
. . c

. T1111: g-.:...1I.1
The granodiorite 1'11'1'. " 1'1-51
of the :11: Turbo
11 1.111 1111.11area has 111-1:". 1'achieved
11'11'111111'11111 its11:11. present
present. 31111111051110”
composition by '3? re- “31
11:11.111111111111111. and
crystallization 11113111111111.11111-1111 of
111111 metasomatism [.11'111—1:111.~'111111111111111111111.-
1-1’1' pre-existing materials, exemplified exe111p11fied by 111' thethe por- 11111—
;11111'1111111111111: growth
phyroblastic 1111-2111111 of 111111-11111-1'111111111' and
111-1111 potash-felspar
1111' both 1.11.1 51111.1
111.111 plagioclase in 111-211111111111
111'11:111111:11111' deformed
111 a1'1 dynamically
1111111111111. the
1111111111111. medium,
granitic 11:11.25. of
1.11111111l.11i11.1:d relics
1111: granulitized 111' which 1111111111 have 11111111.: sometimes e11n1ple‘1e
1:111:1111e11 complete
11.111111111111111 escaped
1'11—1111-111113 111-1.11. Outcrops
re-crystallization. I1'3'111111111111. are 1111111111111: and
111.: massive 11-'e11—j11.11111e1'J_. and
11111111 well-jointed, 3111.111" of a:1 more 1111pe1111~
1111111111111 appear-
111 11: uniform
11111111. than
ance 111111 of
1111111 tbat 111 the 11e1g11b11111'111g granodioritic
111'111'11ge neighbouring
11'1e average g1'1111111d1_111111: migmatite. 11.11 1.111.111.1111:- The 1111111111111 is
1111: foliation 111
111-defined or
ill-defined 111-1.1e111. and
111' absent, 1:11.11111I1. are
111111.11: crystals
111111 quartz 1.11I'11e1e11111- large
.'11'1: sufficiently 11141421: to 11111111111111: from
1.11 protrude 11111111.
111-1'1 '111'1111. imparting
-".e11111L11.':1:1 surfaces
weathered 1"111111111111111' appearance
1111L111_1.'1I'.'111e1'.1 vermicular
11111111111111: a1'1 roughened 11p11e1111111ce to 11:1 the 1.1111111111111111.-
1111': exposures.
T111: rocks
The 111:1: often
1111:1111. are 111111111e1i with
11|11:11 dappled 111111 pink 1:111:1'11111111e porphyroblasts,
1111111 microcline 1e11e111b11-11g the
1:11:11'1311111'11'1111111111. resembling phenfl-
Lhe pheno-
1'11'11111. of
crysts 11111111111111: granite
111' a:1 porphyritic g1111111e or 31111111111111111e- Xenoliths
1:11 granodiorite. 3116111111111 are :111: generally 11.-1:1]-
1.111111]- well-
1_1_e11e1:.1111,1 smaJl:l,
1'11111111e11-11111i 11111111111111.1' 1111111-1111 111.1111 111 C1111-1111'
rounded, and comparatively light in colour by comparison with the large dark angular 1. 1. 1 1; 11111111111111.1111 11.111. 1111: 11111.11: 111.1111 31154111111
inclusions 1.11111111111e
11112111111.111.1 seen in the adjacent 11111.1'11111111e11.
111111111111 migmatites. - .
111 thin
In 11111111111111.1114: of
11e1111111-. porphyroblasts
11111 section; 11111111111'11111e are
11.1" plagioclase 1111111131111111111; it
1111': conspicuous; 1'1 is 11111111—
1111111111.? oligo-
111 usually
11111111: with
clase fine ablite
1.1111111 fine 111-111111.121: often
111-11.1 lamellae
11'1.1.11111. twin 111111115111'1113-111; the
1111e1'11:11e11.-' saussuritized;
11111-111 alternately 11111131111
1211111111 margins
1111'. crystal
111111'1e11111e1. contain
sometimes 1111111111111 minute 111-111111111111: of
111i111.111': inclusions 11111111.: or
111 quartz 11111:: (as
111' mica 1:11. in111 specimens 34"1'117'1‘ from
111111111111e111. 34/637* [111111
131-111 1111;111:111, and
Soysambu, 714-171-111 from
111111 34/635 1111111 two 11.1.1.1, of
1111111111. WNW.
1111111 miles 111111.111.1111'. .11 Bridge).
11f Hemstead's {311111111111111111111 the
1511.11.11.11. Occasionally the
1111-1111111 achieves
felspar 1111.11112'1111‘1Z'11111-11'1111
111:h1e1-'1::. a11 subhedral crystal form, 11.11111- [1.1.1111
with one 11111: or 11.-1'11 straight
1111' two e1'1ge11. or
1.11111154111 edges, 5111.111."
111111.? show
111' may
("111111111111111-11111113.:111111
Carls bad twinning, as in specimen 15111111111131.1474:111111111111113111'12131.
34/747 from Kaptabei.
1.1111111111'111111111111 usually
.‘1-1112111111111: porphyroblasts
Microcline 11111111111 have irregular margins
111111111 irregular 11111111112. with 1.111111 venriicular 1111111111111:
11111111111111 inclusions
111:.11'111111111111- but
111' myrmekite,
or. 1.11me11111e1. approach
11111 sometimes 11111111111111: a:1 euhedral 111111.11 form,
11111112111111 crystal 11111111111111.1111 in
111111.111 particularly z1111e11
111 zones
111' cataclasis
of m1e1'13e1111e 1111' late
11.-”here microclineof
11.131111111111111. where 11.11.111.111 is
111111: growth 1.11.11'e11111ed in
1:11_'1:11:11:11‘11111]1.-' developed
1:. preferentially 1.11111111—
1.111: granu,
111 the
111111111 matrix,
litized 11.1 in
1111111111111. as 1.111121111111111 34/746
1111 specimen the summit
1"1'1111'1 the
.'1—1-‘T41'1 from 11111111111111.
111' Kaptabei.
111-111111111; of
1111111113111 1111' 34
1111111111111 prefixedby
*1‘ Numbers 111 specimensin
11111:: to
.14 refer 11311111111 collectionsof
11111 regional
1.1113111111e11-1 111 the {Li-1312111311114 SHIV-:11-
1111: GeologicalSurvey,
1:1.1'. 11:13 1113111 of the
1.111111111111i.
Nairobi. . . . .
 Ia
~5
Quarta is
Quartz is found
found in
in strained erjrstals .or
strained crystals or as isolated inclusions
as isolated inelttsii‘tns in
in felspar,
i'elspar. whilst
whilst
ilaltes of
flakes of biotite
hiotite are
are often eoneentrated about
often conce.ntrated about the
the oval
anal or
or rectangu\ar.
reetangular margins
margins of of the
the
felsoar porphyrohiasts
felspar porphyroblasts and and scattered
seattered in
in roughly
roughly orientated
orientated aggregates throughout the
aggregates throughout the
liner—grained groundmass.
finer-grained groundntass. .
lliot'te is
Biotite is usually
usually the
the only ittaile mineral
orily mafic ntina‘al present
present and
and seldom
seldom eseeetls more titan
exceeds more than
use per
five per eent
cent of the rock;
of the roelt; in
in some
some localities
ioealities hornblende
hornblende occurs
oeeurs in
in addition. it prepon-
addition. It oreoon—
derates over
derates ot-er 'biotite
hiotite in
in the
the granite
granite outcrops
outert'ips near
near Morton's
Morton's Bridge
Bridge in in the
the south—trestern
south-western
et'irner oi
corner the area.
of the' area. Micrometric
Itieronaetrie modes
modes andand partial
partied chemical
ehernieal rotaljsses
analyses fortor specimens
speeimens of oi"
migmatitie granodiorite
migmatitic granoitiorite and
and gneissose granite are
gneissose granite are git'en in Table
given in Table III.
ill. 'I—

(c).I -sl
t__:' o: ,oit r o: .o' .-‘ [-.-
.' ' 1 I I

Amphibolites
liios;
Most antoitiholites reeorded in
amphibolites recorded in the
the 'I‘urho
Turbo area
area are oi no
are of. no. great slae and
great size hate been
and have been
t'arirntsigs
variously aitered
altered and
and assimilated h}: the
assimilated by toe gneisses
gneisses in
in tihieh their are
which they are enelosed;
enclosed; itit is
is ot'
of
some interest therefore
some interest theretore to tinei that
to find that the Psidalat group
the Ndalat group of hills t_lltlt’i
of hills rot} is
(7,206 feet) is eontposed
composed
entirei}
entirely oi"of many hundreds ot‘
many hundreds ifeet ot"
of feet of eotnoaratite13: unit'ornt antohiholite
comparatively uniform amphibolite eot'erirtg
covering .an an
area
area of of set-era!
several square
square miles.
miles. hidalat
Ndalat is is :ta eons}:1 etiotis feature
conspicuous l'eature situated
situated some
some ten
ten miles
miles
to
to the
the nest
west of
of Eldoret.
Eldoret. The [he hill
hill eonsists
consists oi" of aa series
series of ridges rising
of ridges rising sharply from the
sharply from the
.‘s'osiani valley
Sosiani to a.a height.
vaffileyto height of about '1,000
of about i_.I.'_}t_.It'l feet
feet above
above the
the surrounding
surrounding eountrjr
country {Plate
(plate 1II,I. fit.
b).
TaoLt; III.-MICROMETRIC
TABLE ii I. J‘s-1 Ill—'T-t-I'JT'siEiTRItT AND
..stso PARTIAL
Paa't'taL Cites-utter. ..-"t.‘s:s.t.s-'.sLs or:
CHEMICAL ANALYSES E's-iii] Ma rit'tt: {in-sts'eititi'LitttTtts
OF MIGMATITIC GRANODIORITES
aso {tsetssose
AND GNEISSOSE {iaassirrzs
GRANITES .

Siaeeimen No.
Ho. 1 '2‘. 3- 4 5 [i T ii El 10 .--‘ss.-.
Specimen
~~!~--=-~~~~I~ Av.
:l

'
—- r-a 4L. ~11 o. oo" "
3
|—a. - -.

' 'r" on "J "

_.
.

-. -.
.-i.'
...
....

% % % % % % % % % % %

:l
'l—

C- -$ -i—'s G‘s -'“-.I D:- . '3

Lu ' ., s.-'\- .
d.. is'a i-Li ; 4L. ers. to E ' "

I
|—
., II:
m at: wa-

.-
s.
-: ea --i 4:. .... U. ...

gs."

ccocoumcm
gs, 42-. .... - .
.-.

Qunrta
.-

,.-i._-

sa e I"' l-..'
.'_ if; to t rein is :-I
,—

Lisa Ifj‘t-I'
.

._
:I

Quartz
CT:

r--
lug.

I; J
4;.

41'0 30,6 32'4 38,9 28'8 35,8 38,6 31.8 29.9 28'4 33,6
7.3-} La}
CI“. ['sJ

its-J
eta hell no

Lia

. dis. is i;- 4; C}. .15., -_'_J .31.}

is;

I'sJ
.n.

M ii: roe l i ne .,
Microcline
.-_-

14.3 24'9 36'3 29.6 28.5 11'8 9.2 24'7 35.2 38'6 25'3
on tea is:- 1...;

a.

i—.—-

Us? [-.J ’3“- 'st3- tat

i'-..J
.

t'siJ‘
1...»)
l 'J

- an: no

U1
no
s5
+

Plagioelase Ailing—sat
Plagioclase Ab7S-S0
DJ

's—l

35,9 39.5 27'1 27.1 36'7 34,9 44,9 36'6 27.6 27'9 33,8
L-FJ

Liv—l
lsJ

tJJ
if ' s:-LA.

L.- r'
L...)
I-J

[-J
.-

_'i ..L. [-:_J It}. oo

Biotito
Biotite
53‘s,

8.2 4,6 3'9 4.2 4'4 7,0 6,6 5,6 6'4 4.2 5'5
-..tJ

Ci t_r.

I‘ 1—.- l 4:.

.l -._..F:
2- r:- I

-
.

[Jr-J‘-

3"! use o is i te
Muscovite 0'5 0'3
i“ "I-I""I

.i--.I
Li}

'l—'

rI“|-i.
'I-—-I'

0.2 0.2 0.2 0'3 0.2 0,4 O.! 0.2 0.2

.a—I-i
'-_.-'
.-'*t ptttite
Apatite 0.1 - — -— — 0.1 ‘3'0,3 U0'1 U“
I—l—t.

- 0.1 0.2 0'1 '0'1

3'
#

Chlorite
Chlorite 0.1 U-
0.1] U
0'1| —
- —
- —
- D
0'2 [l0'2 0.2 —
- t]0'1
t"-’
v:
H

Die
Ore. . — — — — -— U
0,33 [lil—
0.2 - — ['0,6
1 0'3 as
0,6 tl0.2

. [-.LJ
Eras-rite (Mean
Sneeille Gravite
Specific SIZE-Eh;—
ol‘ 5)=2'65
[is-lean of
PARTHI. Carats-treat
PARTIAL Assn-ses
CHEMICAL ANALYSES

Sneeimen
Specimen l‘s'io.
No. ; 33 55 7T
I
—-.—- __

I
% % %
slog ... . ... . ra-sa e- r
C:

,_
6:3;t|”
Cfls

SiOz 72'34 67'76 68'95

gs.

taIaz-U-

a i log.
A1z03 ... . ... . lit-T3
14.73 t T
15.77 15'44
_.-.
U1

tstago
NazO ... .' . 2-94
2'94 so
4,06 5.18
UL

ago .. .... s-sa as

-
-
KzO " 5'54 4'98 1'82
-‘
,

At-tetiji'.s't: J.
Analyst: J. Furst.
Furst.
h-iigntatitie granodiorite.
granodiorite. Soysambu,
.Sot'samhu. eight eight miles
miles SSW.
S‘S‘i‘f. of
oi Hoey's
l-[oeje‘s Bridge.
Bridge.
I
shes gases Alissa's:- _.Ls_-l—~
DJ

1. 34/637 Migmatitic
Migntatitie
Migmatitic granodiorite. Hemstead‘s Bridge, Bridge. eight
eight miles
miles north
north ofof Turbo.
shaman-mafia;
sad

2. 34/657 granodiorite. Hemstead's Turbo.

5.1333 Cineissose granite.
granite. 1,000
Lilith yards
t-‘itrds east of Turbo.
'l'urho. .'
be

3. 34/663 Gneissose east of

'tfifi Ti—‘Iigrttatitie granodiorite. Sosiani river
rit'er at at 'l'urho.
lea—.3

4. 34/665 Migmatitic granodiorite. Sosiani Turbo.

' ' Gnoissose
Gneissose granoi'litn'ite.
granodiorite. .fiirabeltepuk.
Arabchepuk, two two miles
miles south
south of of Tur'oo.
C“-
“...-J

'5. 34/667 Turbo.

ssa

' '3] Mign‘iatitio gt‘at‘itniiorito.

granodiorite. Knhiernet. ttine miles
miles south
south of Turbo.
'~.-sJ

6. 34/681 Migmatitic Kabiemet, nine of Turbo.

7. 34/684 84 l‘stigmatitie
Migmatitic granodiorite. Kahiernet. 10
granodiorite. Kabiemet, ltl miles
miles south
south ofof Turbo.
Turbo.
Lu

1U Migmatitie
Migmatitic granodiot'ite. Sosiani river,
t'it'er. five miles south-east
south-east of 'I'urho.
'-_-s.i|

8. 34/710 granodiorite. Sosiani five miles of Turbo.

.rae IrCarieissi'ise
Gneissose granite. Kaptabei. titrefive miles south of
of Turbo.
r_.I-.i| on ‘

9. 34/746 granite. Kaptabei, miles south Turbo. .

5'3 '.

Gneissose granite.
granite. Kaptabei,
Kantaoei. six sit-t miles
miles south
south ofof Turbo.
Turbo.
'—I

“rs-l
“-sJ"

10. 34/747 Gneissose

 113
16

north—eaat11-1ard dipping
generally north-eastward
l'vlassiye generally
Massive garnet—amphiholites outcrop
dipping garnet-amphibolites on the
1.11.1tero11 on the
steep slopes of
hill slopes
steep hill Kahlarnnlti at
of Kablamulu at the n11rth-111-1estern end
the north-western end of of the massif. and
the massif, and areare inin
eontaet with
contact gneisses and
mylonitie gneisses
with mylonitic sheared talc-actinolite
thin sheared
and thin schists tapeeitnen
tale—aetinolite aehists 3—1 13311.
(specimen 34/671),
at the
at hase of
the base tlte hill.
of the Else111-'l1e1'e the
hill. Elsewhere limit of
the limit 11n111hil1ol'ite outcrops
of amphibofite follows the
elosety follows
11.1111ero11s closely the
boundaries of
boundaries the hills,
of the and the
hills. and indieated structural
the indicated pattern is
strttetttral pattern 111' a1.1 synclinal
is of aynelinal fold plung-
fold plung-
ing northwards.
ing Speeitnens 34/672
northss'ards. Specimens 34 (172 (Fig.[_Fig. 3c) 3-1133}. are
and 34/673,
31.1.) and typieal of
are typicall of the darlt
hard dark
the hard
green rocks
green roelts seenseen along
along the the easternmost
easternmost ridge ridge of of Ndalat,
T'sdalat. theythey eonsiat
consist of of strongly
strongly
hornblende prisms
orientated hornblende
orientated 1111isr1'1s and
and pink garnet in
111111; garnet in an
an evenly toliated matrix
e1enly foliated matris of andesine
of andesine
and quartz,
and 1111111111.. the
the average
a1-1e1'age proportions
pro11111rtions of of which
11111hieh are
are hornblende
hornhlende 50 5111'} per
per cent,
eent, garnet
garnet nine
nine
oer cent,
per eent. andesine
andesine 25 2.3 per
per cent,
eent. quartz
1111111.: 2424 perher cent,
eent. sphene
sphene and and iron iron oreore oneone perper eent.
cent.
S11eeime11s 34/678
Specimens and 34/679
3—t_ {fill and the same
11111111 the
3—11 {131} from loeality. are
same locality, similar in
are similar a1111earanee.
otitss'ard appearance,
111 outward
hot in
but in thin
thin section
seetion the the. former
former is is seen
seen to to contain
eontain diopside
diopside in in addition
addition to 111 hornblende
hornblende and and
garnet. while
garnet, appears in
ziosite appears
111-1hlle ziosite in the latter.
the latter.

Throughout their
Throughout their outcrops
otiterojos thethe garnet
garttet amphibolites
amphiholites are are distinctly
distinetly foliated
foliated and
and in
in
some exposures
some esposttres present
present aa stratified
stratified appearance
appearanee due due to
to the
the aftternation
alternation of of bands
hands ofof dark
darlt.
garnet-free amphibolite
garnet-free an1111hiholite or or hornblende
hornblende gneiss gneiss with 11'ith coarser
eoarser garnetiferous
garnetit‘erotis amphibolite.
amnhiholite.
.1‘11n almost
An ahnost rhythmic
1'l11thn1ie distinction
distinetion between
'11et11111een the
the two 111.11 clearly
elearly represents
represents original
origin-.1] differences
ditiereneea
in the
in the lavas
las as or
1111 tuffs
tot'l‘s from
1111111111 which
1111hieh the
the rocks
roelts were
11111.11'e probably
prohahly derived.
deri1ed.

Thin brown
Thin hro111n anthophyllite
antl1o11hsllite schists
sehists ts11eei1nen3—t'hltt.
(specimen 34/674), andand green
green glistening
glistening tremolites
tremolite-
:-111.1ti1111_1litesehists
actinolite schists l[sheeimtn 34 t_'1T"-t"1.1. are
(specimen 34/676), are intercalated
intereitlated in
in the garnet a11111hiht1lites
the garnet amphibolites on on the
the
north—eastern ridge
north-eastern ridge of hidalat.
of Ndalat.

It 1'C-11't'.1.t:1L.111'.111131's.
(2) CATACLASITES, 'MYLONITES 31111111111111.11 AND
1.11121 PHYLLONITES
P1111L1:;:1s1.1Ls

The dominantly
The dominantly gri1n1'1eli11ritie
granodioritic rocksroel-ts of the western
of the western half
halt of
11.11" the
the area
area eshihit tl11.
exhibit the
ell. ee sot
effects of eat-ariasis
cataclasis and and er1s1111 l1111|1s111. det
orystalloblastic t1r111ttiio.n on
deformation on 11a regional
regional scale. lloeits that
scale. Rocks that
lit elt[te1ttttr'.1l
lack e11'i11'ene-1. of
textural evidence hitting undergone
of having undergone shearing
shearing :-1t.11:11_1n111a:1ie1.1l
accompanied by hy internal
internal d1.s1.111ti1111
distortion
and rttotttre of
and rupture 1.11.1 their mineral constituents,
their mineral eonstitttents. followed
follossed by
hy the
the 1:1etas-:.11111-.1'.i1:
metasomatic grossth growth ot
of
lels11ar. are
felspar, the eseeption
are the than the
rather than
exception rather rule.
the rule.
deformed rocks
The deformed
The are classified
r111elt.s are tinder three
ela ssihed under headings:—---
three headings:-

C““ll-"'1‘"-53.1335-—Ci—‘111T5€-ET1‘1llls‘tl Hulls”
(”l Cataclasites.-Coarse-grained
(a) gttes sae and
augen gneisses 111131i1"-t‘1it ie gneisses.
and mylonitic gneisses.
(b) Mylonites.
{1:1 .I :13}- 'IrIIJ IFI-lrlrL '3 .

lt JP11‘1'1'
(c) 11'1— t‘es‘.
Phyllonites.

lit-l Cataclasites
(a) [311.51111:11.151‘111'
I'll | ..-"-l
(i) Augen ll: .F3-.'.-".11.11'1'-1_111
111311.11 Gneisses
Augen gneisses
Augen gneisses are are found deformation zones
in deformation
1111111111 in annes of eonsiderahle width,
of considerable they
11111here they
111idth- where
assoeiated with
are. associated
are '11ith thin mylonitie sheets
thin mylonitic sheets in i11u'11hieh t'rttshing and
which crushing milling of
and milling 111‘ thethe 1.'1_1r1stit1_1-
constitu-
ents have
ents heen more
l1111111e been eetite. The
more acUite. gneisse are
The gneisses are well diaoiayed in
11'ell displayed itt the s11ttti1—111.es1.er11
the south-western
foothills of
foothills of the the Cherangani Cherattgani hills hills in hrnad the
in a'1. broad beltit between Hi11l111_11tet and
het11ee11 Kipkoitet and
l'\:1111se:1'-.1.;1. and
anti Kapserwa,
are also
are also to to be he seen seen in tfi-h1osera valley
the Chepsera
in the salley east east of H1111se11111. They
1.1t Kapserwa. ltey alsoalso occuroeettr in in
:11agt1il'iee11t thrust-sections
magnificent thrttst— seetions in the Nzoia
in the about three
1.111rge ahottt
l‘szoia gorge miles west
three miles 11 est of11_1|i _He111stet'1d's
Hemstead's
Bridge. in
Bridge, the Sergoit
in the Sergoit river 111er one mile east
one mile east of Tttrho near
ot Turbo, Hahiemet school,
11e=.1r Kabiemet se111111l. and and at the
1.11 the
north—ssestern extremity
north-western estretnity of Kelsi-11:-
ot Ndalat.

The atigen
The augen gneissesgneisses are are greygrey rocks with thin
roelts with thin felspathic 1ei11s and
t'elsnathie veins and aa marked marked
1i1terrti111ed hy
t't1liati11n interrupted
foliation lentiettl11r or
by lenticular or typical "eye-shaped" 1111111111.
t1_r1ie11l. “eye—shaped" augen. The The foliation
foliation is is
imparted by
imparted hy thin streak1 or
thin streaky or lenticular aggregates of
len.ie11l:1r aggregates and granulated
strained and
111‘ strained granulated quartz and
11.11111111111. and
lanti111a1.i-.111s af
1111111111111 laminations
wavy hintite. The
ot' hioti,te. matris is
'l he matrix is af tine to.
o'-:' fine mediem grain
to medium eontains large
and contains
grain and large
oligoclase and
oligoelase and microdine porohyroelasts. as
mieroeline porphyroclasts, as in in speeimens
specimens 34/7013—t Ttlt from .'.1e her
171111111 the go
Sergoit
yalley two.
valley miles east
two miles east of T'ttrho. 34/736,
111c Turbo, from two
31.73.11. firom miles south-nest
t11'o miles south-west of Ktthiemet school,
of Kabiemet sehot. !.
1.111113 _3-l
and 35:3, from
34/755, 111111131 111iles
t‘r1'1r11 itwa nest of
miles west Hetttstead's Bridge.
of Hemstead's Bridge.

t:: i:!
 17
17

Lets
As might
might he be expected
expected thethe cempesitien
composition ef of the
the cataelasites
cataclasites is is semctimes
sometimes related
related to
that ei
that of the mctamerphic rocks
the metamorphic recks through
threugh which
LLLL-L'hich thrusts
thrusts and aenes ef
and zones of deferntatien
deformation pene-pene—
trate: for
trate; fer ins'tance,
instance. specimens
specimens 34/642
34.9642 andand 34/76434,"?64 from .i'retm the the Kipkoitet
Kipkeitct valley,
valley”. contain
eentain
trails of
trails ef fractured
fractured garnet garnet derived
derived from
frent the the garnetiferous
garnetifereus gneisses yyhieh hay-e
gneisses which have heen
been
in powerful
ittLL'eELL-Led in
involved peysLeriul thrust nteyements- The
thrust movements. deferntcd rocks
The deformed reeks of Turbe—Eitalc
the Turbo-Kitale
ef the
t'eundatien on
foundation en the ether hand
the other de not
hand do generally appear
net generally appear to carry garnet
tLLi carry perphyreclasts. but
garnet porphyroclasts, bet
shreds of
shreds ef hornblende
hernhlcnde are arc common
cemmen wherewhere the the caJtacIasites
cataclasites eccur occur in in hernhlcndic
hornblendic grane—
grano-
dioritic migmatite. for
dieritic migmatite, esample in
fer example specimens 34/703
in specimens 34,?t (Fig. 4a), frem
(Fig. 4a”). from Sergoit yaltey-L
Sergeit valley
Line mile
one mile east
east of t'tf Turbo,
'i'urht't. and
and 34 7'34 from
34/734 frttm the the Kaigat
lLs'Laigat river
riyct' six
sis miles FEEL of
miles ESE. ttf Ndalat.
T‘sdalat.
Many of
Many ef the
the cataclasites
cataciasites contain
centain epidote
epidete granules,
granules as as in in specimens
specimens 34/477
34 4T? from
frem three
three
miles tterth ef
ntiles north Meihcn post
of Moiben pest ethce.
office, 34/683 item see
34 t’LiiLi'Ei from 300 yards LLyest er
yards west Hahicmct schnei.
of Kabiemet school,
and 34
and TU? from
34/707 liren't titlil yards east
800 yards east uf Buckley Bridge.
of Buckley Bridge.

iiii Mylonitic
(ii) GLLLL'LLLLLLt-Ls
.‘L'i'LL'tLLL'JL‘l ti' Gneisses
lestures of
Textures the mylonitic
Ltd“ the gnLtssL are
rnylttnitie gneisses are intermediate hetytecn those
intertttediatc between tht'tse of steamer
the coarser
”t. the
catac
cataclasitesLLLLsiLes attd true mylonites.
and true mylenites- They They are are dark
dark strongly-foliated
strengly—reliated rocks reeks often
eften containing
eeLttL'LinLng
strings of
strings et felspar
tclspar or er quartzquartz ,porphyrocIasts,
perphyreclasts. as as initt specimen
specimen 34/630 34"630 from irem the the Little
Little
T‘sLLLttiLt river
Nzoia riycr at at Ziwa,
Zitya- and anti 34/649
'34 (L45l from
tirem thethe Nzoia
is'eLtia river,
riyer. ,two
L'LLLLL'e miles
ntiles west
LLLLest of
Lti‘ Hoey',>
Htteys
Bridge. A
Bridge. .--'\ delicate
delicate wavy LLLLLLLLy foliation
feliatiee is is often
ett en produced
presceLl by by thin
thin lamellae
iLLLiLzeiiae of
et' biotite
hietitc and
and
dusty iron
dusty ire-n ore, ere. andand is is well shnyyn in
net] shown in specimen ian the
34 t'Lt'LLL.) from
specimen 34/669 LLL'Lrth-LLyest eerLLer
the north-west corner of Lit"
Ndalat.
H t'LiLL'LLl'Lt'L.

lfu't} Mylonites
(b) Utirtttttts

myletnitcs are
Tite mylonites
The black. very
are black, hard. splintery
yery hard, interealated as
reeks in1ercalated
splintery rocks sheets in
as sheets in
LtLyiLinitiLL and
mylonitic and augen
Ltttgen gneisses
gneisses of er the
the major
rttajttr zones
zenes of
t'tf differential
ditiereittial movement
tttny entent (plate
t'l’late V,”LC. b).
,L'L:_
they are
tithe-Legit they
Although eempact or
are compact dense. and
er dense, and might thcrctere be
might therefore espcctcd to
he expected erLLsLL
resist erosion,
tLt resist
in point
in of fa(:t
petittt of their high
fact their iissili-ty permits
high fissility rapid weathering
pern‘tits rapid and in
LLLyLathering and cttitsequettee they
iii consequence tile}
L-LL‘e often
are Ltitert poorly
pL.LLtrly exposed.
esptt. .ed.

The rocks
The reeks can
can be
he seen
sees about
L htt-ut two
‘LLLLL-Lt miles
:tLics west
LLyesL of
L” '" Ndalat
"sLiL-Liat in in the
the broad
hire-Ltd valley
tLLLLley between
tL-LLLL'LL'LLL
Htthiantttlu and
Kablamulu Hap-take L and
and Kaptabei; and ttg agann Ltirt ttt.pcat'
appear in in the
the Sergo
.‘Liet it it river
riLLLer an.an;
about nne one rttilc
mile 1n to thethe
tst of
east Turhe and
ei’ Turbo and also in the
alstt in stiLLLrtL-sLLLLtLLLn to
the stream-section tn the nttrth ei
the north of Croxford Bridge. The
C_rL.tstLtL'd Bridge. lhc
Tsaeia gerge
Nzoia gorge seme Lhree miles
some three Ltiiles west
LLLLest of er" Hemstead‘s
Hemstead's Bridge Bridge contains
eenLains sections
seetiens whereLLLL here the the
riser crosses
river cresses thethe strike
s'rike ofLit' mylonites
mylenitcs and and mylonitic
mylLtnitic gneisses.
tcL sses. Mylonites
L‘ylylenites in in the
the lowerieLLLe-r
.111: is of
parts the {'_herangttrti
er the Cherangani hills stLLLessLLtt" can
hL lL s succession can behe seen
seen in in thethe Moiben LLLtlley near
Nittiheh valley HaisLLt‘L
near Kaisagat
and
and in iii the Kttpsettsa hills
the Kapserwa hills one
tttLe mile
tttile to tLt the
the north
Ltttith‘Ltir l-L'LLikttrLat-LLLL.
of Kokorowa.
In thin
In sectiert the
thin section the mylonites
Lttylenite-s are tine-grained streaky
are fine-grained reeks rendered
streaky rocks rendered darkdark byby dusty
dLLsLy
sLLLhmiLLLLLtscepic iron
submicroscopic iren oree-re and mica. The
and mica. he matrix
matris .Df minutely granulated
of minutely granulated quarts
quartz and and
i'clspar is
felspar is foliated
liLL'LiatcLLi and intensely shredded
and intensely shredded intoit'ilt‘t strain-polarizing
s rains LLL.LL.LLLLL"LLL aggregates
aggregates enclosing
eLtLlL‘LeLg
lL'ttger distorted
larger tiistetrted t'tr sl‘Lttttered porphyrodasts
or shattered perphyreelusts ythieh
which have hate escaped eL tntpletc milling,
escaped complete ntil1Line. as
ts
in specimens 34/643
in specimens 34-643 (Fig. (Fig. 4h].
4b), from the Kipkoitet
frem the yatley. and
Kipkeitet vaHey, 34 TEL-‘3 from
and 34/758 mLies
three mrles
item three
ctstead's Bridge.
elt' Hemstead's
'LLLcst of
west Bridge.
The degree
The degree of ttl‘ cataelastic det‘LtrL't'LLLtit'in often
cataclastic deformation Lil‘iCi] varies
yaries .in in aLL single
sitigiL-e Ltoutcrop
LLtLLL Ltp from
item normalItertt‘tL-L.
In extreme
to extreme mylonitization
myl-LtnitLLLL-L'L'Littn citetttpliiietl
exemplified by by thin thin filmsfilms or Ltt' sheets
sheets of tit glassy
glttssy ultramylonite
'LL'lt.L""LtntyletLit'e
rarely more
rarely mere than than Lta few t’ety inches
inches in irt thickness,
thickness in which the
in which t'inely agrrettnd matrix
the finely-ground matris canttetcannot
he resolved
be resttlycd under under the the microscope.
nLLierL'tscepe. Even Eyen here, here. however,
hLLLLLL'eLLer. aa few
ten almost
Ltlntest perfectly
perfectly-L rounded
rttttnLi-LLL'L'
pL..'LpiL.yrt.-L asts remain,
porphyrodaSits rentLtiL ‘LL andand like
like thethe larger
'.LLL'gei' porphyroclasts
perpityreelttsts ~n in the
the less
less intensely
intensely deformedLietrtttee
ntylLLLtites L-tlset
mylonites indicate parent
also indicate parent rockL'Ltek type. type. 'lhus Thus in irt specimens
specimens 34/599 34 sat-L from t'rL'tnt Kokorowa,
KttkttreLLyL-L.
34. T15 and
34/715 34.7.]? (Fig.
attd 34/717 r'reni two
4c]. from
thig. 4c), titles west
tLLLLLe miles LL. est of T‘sdaiat. the
et' Ndalat, perphyreciasts are
the porphyroclasts are
eiten fragments
often tragments of Lit" strained
strained ettarte—iicispar
quartz-felspar aggregates aggregates similar similar to te that
that of til" the
the matrix
matris in in
the neighbouring
the net ghhetiring mylonitic ntyietnitie ttr augert gneisse.s
or augen gneisses. Specimen Speeittten 34 till from
34/611 frent three three miles mites
ss. E. of
S.S.E. et Kapserwa,
l‘iL'L-L'ti'i‘sell'fli‘i- isis an
an unusual
unusual. type Lypc of el' lineated
lineatcd white Lshite mylonite
mylenite outcropping
L'LutcrLtppiLLLg on en the Lhe
eLtrtt inLt'L-LLiL'tn of
continuation Ltt' basal qLLLLL'tritcs of
httsal quartzites Lii the tt‘tcLL-Lsedimentary rocks.
ti."i‘terLLLngL-"Lrti metasedimentary
the Cherangani incits. In in thinthin
seetierL it
section seen to
is seen
it is tn be he composed eLtt:L'--L'L-.‘_-L of
ettrL'LpttsLLLl entirely Lt! strained granules
Lpit'trttt granules.
strained quartz

iP
 18

I.
0L- 2l'.
~ ,mm.

(a)
(a) {ll}
(b) {1"}
(c)
Fig. J—Ih‘flhiflgh
Fig. 4-Drawings ul' thin sections
of thin hen-tinny; of
[if wllenrerl melee frnin
sheared rocks from the l-Llrlnret area;-
the Eldoret area:—

tilt
(a) _-'tl1f_{E]'l
Augen gneififii.
gneiss. Speeinien
Specimen 34 703. t'rnm
34/703, from Line
one mile
mile enat
east nf
of 'I'urhn.
Turbo.
flrdinary
Ordinary lighti
ligbt, W“.X 13.
[3. Quart:
Quartz 1Q}.
(Q), Flnginelnee
Plagioclase tl-‘t.
(P), Binlite
Biotite and
and
l-Iernblenrle (B).
Hornblende {El-t.
[ht Uglnnite. .‘ipeeinten
(b) Mylonite. Specimen 1—16-13
24/643 frnm
from Hipkniter.
Kipkoitet. L'rnfiiierl
Crossed nieels.
nicols, X--’. 13.
13.
Quart:
Quartz {Q}?
(Q), Wilerneliite
Microcline [1]],
(M), PIEigiflL‘illl-Ffl
Plagioclase {1’},
(P), Herieite
Sericite :Inrl
and irnn
iron nreore
in matrix.
in matrix.
le'tlh'lnuile.
(c) fipeeinlen 34/717,
Mylonite. Specimen 34"?17. from
frrnn two tu-n miles
miien west
neat til' H'dnlill.
of Ndalat.
Urrlinnr} light. X 13.
Ordinary ligbt, 13. Quart: tut! Felspar
Quartz (Q), Pelt-4131* {FL
(F).

(c) Phyllonites
[Lil PEER-sill};{ii-lily}!!-

Finevgrnined Sehietnne rocks

Fine-grained schistose melee nwing their delicately
owing their eleheiitely folia.ted
feliateel texture
texture and
and fianile
fissile
.ipnean'iinee
appearance in to extreme
extreme eletinrninzien
deformation areare eenn eiit'inirely' rare
comparatively rare inin the
the area,
area, htit nere
but were
reenrded in
recorded in the Hipharren vaney
the Kipkarren mile}: in
in <the
the snuth—neetern enrner of
south-western corner at the
the area.
area, and
and inin the
the
1Cherengiini
Cherangani fnenthilis.
foothills.

Speeinien
Specimen 34.594
34/794 frntn
from altlil yrirele east
400 yards ef Rneeei'e
east of Bridge. Ea
Russel's Bridge, is LLa fiiiggj; ginl: rneie
flaggy pink rock
with
with. aa closely
elnselj.‘ epeeed
spaced Streaky:
streaky, green fnliatinni {LI'LLl
green foliation, and dapp ed with
dappled nith eneili
small clerk
dark green
green
nerphyrnhlneta. 1n
porphyroblasts. In thin seetien it
thin section it is
is seen
seen toin be
be enleiireeus, with Liz-tr};
calcareous, with dark lamellae
lamellae enntein-
contain-
ing biotite,
ing hintite. hornblende
hnrnblende and and green
green diopside.
dingsiele. TheThe finely
finely granulitic
gr'nnniitie and
and felspathic
felenathie matrix
matrix
en iteins small
contains snn‘ill granules
granules ofof sphene
ephene and
and nnzitiie.
apa-tite.
Sneeiniene 34/641
Specimens men from
t‘rntn Kipkoitet
KlpkttilE‘l and
Ellf'lLl 34/601
34 till] from
tirnm Kokorowa,
Kill-it'll'L‘I'al-fl, are
are niieneenue
micaceous
nhjr-zllenites with
phyllon.ites n'ii‘n thin
thin wavy
net-'3' foliations
feliatinne of
nf muscovite
ninaenrite and
nnei chlorite,
ehinrite. both hnth occurring
neeerring in
in
tltrnnt-znnee.
thrust-zones.

EIETmIrint’ttuz-nji SEDIMENTARY
t3.l METAMORPHOSED
(3) ‘t'rne.~.:-:tr' ROCKS
.tHiJ VOLCANIC
SEDEHEWTAR‘L' AND 'itii; CHERANGANI
rn' THE
Helen‘s OF HILLH
Cingnwea m HILLS

{erming the
Rneka forming
Rocks rinnthern Cherangani
the southern group dis-:inei
Cetl‘lrillitlit .a21 group
hills constitute
Cherengiini hills freen the
distinct from the
rnnnetennns migmatites
monotonous niigrnritites and
and granodiorites
granndinritea occupying
neenpying the the western
n'erttern part
part of
nt" the
the area.
lll't'i‘ét. The
The
Cherangnni rocks
Cherangani renrenent the
rne‘ee represent CCflll‘r‘é‘llCfllS of
nietiininrnhie equivalen.ts
the metamorphic at aa differentiated
differentiated marine inarlne
sequenee which
Heelintentary sequence
sedimentary were probably
whieh was elepetiited on
nrnhably deposited nn a:1 continental nhei‘t‘.
enntinente] shelf.

.... ;.
 19
19-

For descriptive
For deseripti't'e purposes
purpesee ;the
the rocks
1111:1111 are
t1re described
deserihed under
under the
the following
17111111111111; headings:-
heading:
-1111111.11111rp1‘1111ed 51111111111111.1111 Rocks
Meta_morphosedSedimentary 1111111111-
(11') Calcareous
(a) (71111111111111.111- Rocks
1111;11:111-
(1'1 Crystalline
-(i) Crystalline. limestones
lirrtestpnee (marbles).
(fi'tfll‘hlfi‘fi).
1.111111111111111e11111e gneisa
(ii) Wollastonite gneiss and rock. 11nd re1e11.
{111'1Celet1ree1111
(iii) pare-gran1111'1e11. para-gneisses
Calcareous para-granulites, para-gne111e11 and
11nd amphibolites.
t1tt1phibe11te1.
[111) Skarns.
(iv) Sheree

{1111131111111
(b) Pelitic Rocks Rt'iekt
[1] .1111-‘11111'te1gt1rr1et-h1'1'1tite
(i) Kyanite-garnet-biotite schists. 111211111111.
[11") Siltimanite-garnet...biotite
(ii) 11111111111.
Si111111111111e-e11rr1et-1111'111'te schists.
11111 Kyanite-sillimanite-biotite
(iii) 11121111111.
1(1'51111'1e-11111111 t111ite-1i11'1'1tite schists.
(iv) Gerttetitet'etls schists.
{11'} Garnetiferous 1e11111111.
(v) 11eht'11t11.
G1't1p1'111e schists.
1'11"} Gra:phite
(1'1")131311111111-p11rp111'1111_11111t
(vi) Felspar-porphyroblast .e11e11111e1.
gneisses.
r l' I I I

(c) Semi-pelitic Rocks - 1. 1

1.11" .1 Psammitic
(d) H .1' 11"1'1.‘ .1'
P111111 1:- 1‘ 1‘1.-"1'” Rocks
{1"} QUELFIEHEE 111111
(i) Quartzites 11111.11e1111'1e 1.11111111111e11.
and muscovite quartzites.
('11) Quartz-felspar
(ii) Q1.1ttrt.E-fe11'1p11r para-granulites
pt1rt1 grahtthteH and 111111 para-gneisses.
pertt-gtteiafiefi.

.1 [11.111 .1 1.1 11-_111’.11.'1 -. 111.1 Volcanic

Metamorphosed 1 '1 1111-1 11 .113 1 1111.11
Rocks
111“] 1111r1111-1e1111e
(a) Homblende gneisses and 5411611111111 111111.11111r11'1i'r11'11ite311.
.amphibolites.
111111111:-111_1r111'11e1111e gneisses.
1.111} Biotite-hornblende
(b) 5-1111-1111-1.

1.11:1 Calcareous
(a) {1'1'1‘1'1IT11'1'1'111-11.‘ Rocks
1'1-‘51 if; '.1'

Pure crystalline
-Pure the rare
".-111':-:':111'.111e.1'1 are
e1r1=1111111111e limestones tire. in 111 the 11111111111111 part
the southern p.111 of 111' the 1111}-
11"11e1'1111et111'1 hills
the Cherangani
the}? are
111111 they
and 1111.1111e1111e1'1 with
t1re a~sociated g1'tt1111111e1 and
1111'1'11111e1'i granulites
111111 stratified 31111215111111; 11111111311111.
;-__Ti1e1'~111e1 containing
11:11.1 gneisses diopside,
11p11e11e and
ep11111te. sphene
epidote, lime-earner representing
11111! lime-garnet, rept'ez1111111r._-; 1111;— the metamorphosed 1:11111'1111e11t11 of
11111111111111'11'111'1-ted equiva'lents -.11'
ett1e111'e111111
calcareous 1.111111111111111
sandstones 111111 and 11111111.
marls.

['11 Crystalline
(i) £'1'j.'.111'11'1’1'11e Limestones
E'_1'.1..11-'~'.-'r.1111' 1' (Marbles)
1.1111111]
The best
The e'-~'.p1.11:~1.11'e11 of
heat exposures 1.11.: crystalJ:line 111111-1111t1e are
121-1-‘1111'112'11e limestone :11 be
1111': to 11ee11 in
111: seen Nether. 11111."
the Moiben
1'11 the river
at ‘1'1'51111'11 it
ptt-itlt where
111'. a:1 point 11 flows 111re111gh a11 narrow
11111113 through _:1, about
1111111111 gorge 1'1_'11.tr mi'les
1111121111 four 111111111 111'
11111e11 south 1115111511111
of Kapsiliat
("3531.1 feet).
1111111111111 (8,539
summit 1'e1:11. They They are e11-'.1tt1111'11e pink
e11111'11e11; crystalline
111-1: coarsely pink and 11t111e rocks
1111.11 white 1.2111111111111111
1111:1111 containing
111te1't'111111t1111111 of
interfoliations 1111e-11'11'e111e minerals,
1.1t' calc-silicate p1111'11111p1'te or
11111111111111. phlogopite graphite. together
1'11' graphite, together with 1e11t1'e111t1r'
111111 'lenticular
111e111111111111 of
inclusions 111" dark ere-e11 or
111-1111. green 1.11 brown gr1111111111e quartz-epidote-pyroxene
111111111: granulitic
111111111 finely 11"..11
1.1111111. that
1111;11:11t-ep111111e-g11.-1-111.1;e111:1 skarn,
e1fte11 project
often p1'11jeet from 1'1'11111 the 11111111111111- weathered
the smoothily at the
1111't'ttee11 of
11.e11111ere11 surfaces 111111:~1111:1e.
1:11e1111111:1I 'limestone.
the enclosing

111 the
In- the Moiben
Methen river 111'er three
three paraUel
1311111116 limestone
Ein1e1111111e outcrops,
111113111111. separated
1.1-pt1r111e11 by 111' homblendic
hertthletttfie
11nd eate-atheate gneisses,
and-cak-silicate g11e11111e11. have
11-1111: respective
re1.peet1'1e widths1111111111 of 111' 20
212.1 yards,
111111.11. 15
15 yards
1'1-11111;. and
111111 50
5t yards,
111111111. in
£11
meter from
order 1.113.111 111 east.
from west'to 'i'he interval
et1111. The het11-ee11 bands
1'111e11'111 ,between 1111111111 -is 11111111. and
1.1.1 small, 111111 the three units
the. three ht11'e.
111111.11 have
heert shown
-been 1111111111 as
2111 a1 single
iingle band 11111111 on1111. the
the ma:p.
11111p. Continuations
112711111.111111111111111 of 1.11 the
the limestone
11111e1111r1e. outcrops
1'1L11er1‘1p11 can
131111
he traced
be treeed to 11.1 the
the north
north along11111111; the
the steep
Steep western
111-1111111111 slopes
1111111121 of 111' thethe upper
upper Moiben 11111111111 vaHey,
1'1-111e11. where
11'here
the mean
the 111e:111 strike
1111111e is 1.1 1850
1115' with
111111 1111.111e1'
easterly11- dips
111p11 varying
varying. between171e11.1.'ee11 50° 51.1 111111
and 115' 65°.
bpeeirhen 34/548
Specimen 3—1 i151 from 111111111 of
111111-35 south
three miles
1‘1'1'111'1 three 11111131111111 is
1'11 Kapsiliat 1113111111 111
1.11 typical of these erj.'1'1t:-_111111e
theme crystalline
Iittteitpttes. The
limestones. The. Fpeei111en
specimen is 1.1 11a coarse
e1‘111r11'e pink
pit-111; rock
1'11e1t 1.1111111111111311
composed 1111111111 almost entjre1y
entirely 11f Cttlejte.
of calcite,
together 'with
together 111111111 1111111111111; of
1111111 smaUamounts pale brown
1'11 11a pale p1e1‘1ehr1‘11e phlogopite
1111111111 pleochroic mica 111111
p11111g1‘1p1'te 11111211 and rare r11re.
11 111'1'1'1111111ite.
wollastonite.

-'"W
 Ell
20

Dther outcrops
Other of crystalline
outcrops of limestone can
crystalline limestone be seen
can 'be near the
seen near crest of
the crest ya
|Geben ya
of GeOOn
Mayoto, four
Mayoto, south of
miles south
four milles Chemurokoi summit,
of Chemurokoi where the
summit. where width of
total width
the total limestone
of limestone
is considerably
beds is
beds than in
less than
considerably rIess in the Moiben gorge.
the MoiOOn The rocks
gorge. The pink in
are pink
roe-its are in colour and
colour and
interfoliated with
interfoliated narrow felspathic
with narrow thin section
layers. aa thin
felspathic layers, specimen 34/577
of specimen
section of one
from one
3455?? from
these 'layers
of these
of microcline. oligoclase,
contains microc:line,
layers contains epidote. pale
abundant epidote,
oligoclase, 3!bundant amphibole
green amphibOle
pale green
sphene, together
and sphene,
and with aa sma:ll
together with amount of
small amount calcite.
of calcite.

{ii} l—lrloilosrrmire Gneiss

(ii) Wollastonite Gneiss and Rhett
and Rock
Thin hands up
Thin 'bands to 1
up to 1 foot in width
foot in width of ash-white foliated
of ash-white t‘oliated wollastonite outcrop
gneiss outcrop
woliastonite gneiss
near the
near crest of
the crest Jariget. aa prominent
of Jariget, ridge situated
prominent ridge about one
situated about mile to
one mile the east
to the of
east of
Garamoso. In
Garamoso. In thin {specimen 34/544),
section (specimen
thin section rocks are
these. rocks
34_.-54~‘l]. these seen to
are seen almost.
consist a'lmost
to consist
entirely of
entirely with sma'N
wollastonite with
ot‘ wo~lastonite interstitial calcite.
of interstitial
amounts of
small amounts calcite and few scattered
and aa few scattered
granules of
granules sphene.
of sphene.
Bands and lenses
Bands and grey or
of grey
lenses of pearlycoloured
or pearly-co loured wollastonite rock are
wollastonite rock are also near
found near
also found
to the
to contacts of
the contacts limestone of
the. limestone
of the of the Moiben gorge.
the Moiben The wo~lastonite
gorge. The generally
is genera~ly
wollastonite is
segregated tough and
into tough
segregated into aIlmost monomineralic,
compact, almost
and compact, coarse granoblastic
monomineralic, coarse aggre-
granoblastic aggre-
gates, occupying
gates, occupying ~enses adjacent to
lenses adjacent caIcareous and
to calcareous siliceous gneisses.
and siliceous gneisses.

[iii] {."rtit'trer'Jtrs
(iii) Ford-Grrtrtrrlirr'.s. Para-Gneisses
Calcareous Para-Granulites, Purrt—Grte‘iss'es rind Aritphihidites'
and Amphibolites
granulites and
Gneisses. granulites
Gneisses, and amphibolites formed 'by
atnphiholites formed metamorphism of
regional metamorphism
the regionall
by the oi
mised calcareous sediments
mixed calcareous constitute an
sediments constitute. important group
an important group in southern I‘C‘herangani
the southern
in the Cherangani
hills. They
hil'ls. They are eaposed in
well exposed
are weill in the yaliey and
the vaHey and ridge country between
ridge country and
Kapsiliat and
between Kapsiliat
tljhebtiirorua.
Chebororua, and escellent sections
and excellent sections are
are to to 'be
be seen
seen onon the
the steep
steep western
western slopes
sIlopes of
of
Chenturokoi (9,548
Chemurokoi [9.5433 feet}.
feet).
amount of
The amount
The ferromagnesian and
contained ferromagnesian
of contained cale-silicate minera~s
and ca'lc-silicate strongly
minerals strongly
influences the
influences the colour and outward
cOlour and appearance of
outward appearance these rocks;
of these the felspathic
rocks: the tEarieties
t'elspathic varieties
are pa'le
are pale grey.
grey, whilst
whilst others
others are
are darkened
darkened by by the presence of
the presence of hornblende
hornblende accompanied
accompanied
by diopside.
by diopside, epidote, and sphene.
garnet and
epidote. garnet and grade
sphene, and dense amphiholite
into dense
grade into amphibolite whose sedi-
whose sedi-
mentary origin
mentary only indicated
is only
origin is the constant
by the
indicated by deyeloptnent of
constant development diopside.
oi diopside.

grey medium-grained
.‘yiassiye grey
Massive and gneisses
granulites and
medium-grained granU!lites outcrop on
gneisses outcrop on the slopes
western slopes
the western
of Chenturokoi and
both Chemurokoi
oi 'both Kapsiliat. and
and Kapsiiliat, and can also 'be
can a'lso seen in
be seen the Moiben
in the The
s'alley. The
Moiben va~ley.
rocks haste
rocks marked granoblastic
have aa marked granoblastic texture; quartz and
teature: quartz oligoclase constitute
and oligoclase more than
constitute more than
60 per cent
so per of the
cent of rock and
the rock the remainder
and the consists of
remainder consists pale green
of pa~e diopside and
green diopside pleochroic
and pleochroic
hornblende. with
hornblende, sphette and
with sphene iltnenite. as
and ilmenite, in specimen
as in 34.4% from
specimen 34/476 from the loops
its-'loihen ~oop-
the Moiben
road, three
road, three miles south-east of
miles south-east the ICheborot’ua
of the fork. Epidote
Chebororua fork. Fpidote is accessory
frequent. accessory
is aa frequent
mineral in
mineral in these
these rocks.
rocks, and
and isis sometimes
sometimes abundant.
abundant, as as in
in specimen
specimen '34 4?} from
34/473 from thethe
C'berangai vailley,
Cherangai which also
s'alley, which contains diopside
also contains and scapolite
diopside and scapolite toto the
the virtual esciusion of
s'irtual exclusion of
quarter and
quartz and felspar.
fclspar.
Gneissosc— cakareous
Gneissose rocks are
calcareous rocks common than
more common
are more yarieties. In
granulitic varieties.
the granulitic
than the some.
In some
the coloured
the coloured minerals
minerals are are concentrated
concentrated in in Ibands
bands alternating
alternating with
with felspathic layers: as
felspathic layers, as
in specimen.
in specimen 34 533. from
34/533 front two
two miles SSW. of
mrles SSW. of Irc'hernurolszoi
Chemurokoi (Fig. 5a}. This
(Fig. 5a). This rock
rock contains
contains
green diopside together
green diopside together with
with scapolite
scapolite and granules of
and granules of sphene
sphene and and epidote
epidote inin aa toliatcd
foliated
mosaic of
mosaic of quartz
quartz and telspar. In
and felspar. In specimen
specimen 34,- iii-45 from
34/845 from Still
800 yards
yards south-west
south-west of of Chentu-
Chemu-
rokoi,
rokoi, hornblende
hornblende is is more
more abundant than diopside
a'bundant than diopside and and isis accompanied
accompanied by by scapolite.
scapolite,
sphene and
sphene sodic andesine.
and sodic andesine. Rocks
Rocks of this type
of this type are are intimately
intimately associated
associated with similar
with similar
gneisses
gneisses and granulites which
and granulites which contain
contain little
little diopside
diopside or or scapolite, but whose
scapoilite, 'but whose nature
nature is is
indicated by
indicated by the presence of
the presence of sphene
sphene and
and epidote,
epidote, for for esample
example specimen
specimen 3—1..- 499 from
34/499 from thethe
cliffs
cliffs onon the upper western
the upper western slopes
slopes of Chenturokoi- The
of Chemurokoi. rock is
The rock is essentially
essentially aa plagioclase
plagioclase
amphibolitc containing
amphibolite containing somesome so per cent
60 per cent of
of granoblastic plagioclase. Sedimentary
granoblastic plagioclase. amphi—
Sedimentary amphi-
bolites
bolites ofof this
this type
type resemble
resemble amphibolites
amphibolites of of igneous
igneous origin.
origin but
but are
are usually
usuaNy distinguish—
distinguish-
able
able from
from the the latter
latter by
by the presence of
the presence of small
small amounts
amounts of of green
green diopside
diopside and interfolia—
and interfolia-
tions or
tions Ienticles containing
or lenticles containing epidote or zoisite.
epidote or Specimens 34/471,
zoisite. Specimens 34_.—4Tl._ front
from the Cherangai
the Cherangai

. --"'*
 2i
21
yalley,
valley, and
and 345346
34/546 frcm
frQm Sembeywa,
Sembeywa, are
are typical
typica:l of
'Of the
the calcarenus
calcareous amphibnlites.
amphibolites. in
In the
the
fermer
fQnner rack,
rQck, hernblende
hQrnblende is
is mere
mQre abundant
a:bundant than
than diepside,
diQPside, the
the twe
two minerals
minera'ls tngether
tQgether
censtituting
cQnstituting nearly
nearly cine-halt
'One-half cf
of the
the rcclt,
rock, whilst
whilst aennblastic
xenoblastic elignclaserandesine
dligQolase-andesine and
and less
less
than 10
than 10 per
per cent
cent at
'Of quartz make up
quartz make up the. remainder. Hcrnblende
the remainder. in subhedral
HQrnblende in subhedral prisms
prisms is
is
the
the dcminant
dQminant mineral
minerail inin specimen
specimen 34,5545,
34/546, plagidclase
plagiaclase andand quarts
quartz are.
are rare,
rare, but
but the
the
calcarecus
cailcareaus nature
nature ef
'Of the
the rcck
rack is revealed by
is revealed by scattered
scattered grains
grains pf
'Of dinpside
diopside tdgether
tagether with
with
abundant
abundant sphene and ilmenite
sphene and interstitial between
ilmenite interstitial between the the. hnrnblende.
harnblende. Specimen
Specimen 3455-33
34/583
frnm the
from the scuth-eastern
sauth-eastern sic-pes
Slapes Inf
'Of Garamcsn
GaramQso is is aa ccarse plaginclase amphibplite
CQarse plagioclase amphrbaiite contain-
cantain-
ing abundant.
ing abundant prisms [if zeisite shnwing
prisms 'Ofzaisite showing anemalnus interference cclcursi
anQmaQaus interference colaurs, enciused
enclQsed in
in sndic
sadic
labradpritc.
labradQrite. In
In this regicin dark
this region dark hcrnblende
hQrnMende gneisses
gneisses cf
'Of calcareeus
calcareous crigin
origin are
are delicately
delicately
laminate-t1 with
laminated pale. green
with pa'le green epidete-rich bands each
epidQte-rich bands each aa few inches in
few inches thickness, which
in thickness, under
which under
the
the mic—rc-sctipe {specimen 34,-"585
microscQpe (specimen 34/585 frcm
fram the
the eastern
eastern sinpes
slQpes cf
'Of Gal'élmtliifl)
Garamaso) are are seen
seen tn
tQ be
be
quartac-se
quartzQse and
and finely
finely grannblastic
granoblastic with abundant epidate,
with abundant epidnte. pale
pale pink
pink garnet
garnet and
and scattered
scattered
granules 'Ofbright
granules cf bright green
green dinpside.
diopside.

{its}
(iv) Skurnr
Skarns
Dense unfnrliated dark
Dense unfoliated dark green
green lenses
'lenses and
and ncdules
nadules areare cummpn
cammQn in in the
the calcarecus
cakareaus
meta-sediments. in
meta-sediments. In thin
thin sectinn
sectiQn mest
mast specimens
specimens are are fine-grained
fine-grained andand granublastic,
granoblastic, cunscan-
raining deeply—cclcured
taining deeply-colaured mcncclinic pyrcraene and
mQnaclinic pyrQxene irnn-rich epidcte
and iran-rich epidote in in rQughly
rdughly equal
equal
propertiens, acccmpanied
propartions, accampanied by pink garnet,
by pink ilmenite, and
gamet, i[menite, and interstitial
interstitial quartz
quartz andand labradnrite
[abradQrite
[specimens
(specimens 34,-"484
34/484 andand 34,512}
34/519 from Chemurekt‘iij. Zln
frQm ChemurQkQi). In snme
SQme reeks
racks Llf
'Of this type garnet
this type garnet
is absent,
is absent, as in specimens
as in specimens 34,3483
34/483 and and 34,-".‘334
34/534 aiscalsQ item
from Chemurdkci,
Chemurokai, 'but but inin nthers,
'Others, I

such as
such as specimen
specimen 34,527,
34/527, fromfrom Gilli} yards cast
600 yards east pf Chebercrum garnet.
'OfChebararua, garnet isis the
the dcminating
daminating
mineral. These
mineral. These rec-ks
racks all
aU centain
cantain appreciable
apprecia;Me quantities
quantities et granular iron
'Ofgranular iren ere in the
ore in the matrix
matrix
and
and were
were pessibly farmed frcm
PQssibly fQnned ircn and
from iran and ilime-rich ncdules enclc-sed
'lime-rich nQdu'les enclQsed in in the curiginal
the 'Original
calcarecus sands
calcareQus sands and
and silts.
silts.

Same visually
Same yisually estimated
estimated cQmpQsitians
ct'impesiticns far
fcr the
the ca[careaus
calcarenus rocks
reeks 'Of
pf the
the Cherangani
Cherangani
hills are
htHs are as
as fallt‘it—s-‘si—
fQmaws:-

34.5433
34/473 34.5499
34/499 34.5533
34/533 34,-"54fi
34/546 345585 :
34/585 34.5519
34/519
I I

fl___.-" I} _ (.1 __.-" LII

%e %e %c %
--"'c %c {ll ICI-
%
--"'-:r
Quart:
Quartz .... .... 33 4 3t}
30 + 46
46 8i3
T's-'licrncline
Microcline ... . -—— ---— 7T -
-— -— -—-
Plaginclase
Plagiaclase ... . 4 {it
61 28t 1l -— ID
10
i’yrnaenc
Pyroxene ... 36
36 -— 1:3
15 4 33 40 {l
Scapnlite .... -—
-
ScapQlite ... . 3U
30 IE
12 -
— -— -
___
l-lnrn‘nlcnde
HQrnblende ... . -__ 25
25 - 32
82 -—- -
—
Epidetc ...,
EpidQte ... l?
17 4
4 4 -
—~ 45
45 3‘3
35
lGarnet -— -— -m -—
-
Gamet .. ... . 6El 44
Sphene ...
Sphene ... . t38 2 2E 7T -«- -
~
.4. patitc ..
-
Apatite . . ... . 2E 1l 1l -.___ -—- -—
llmenite . .
Ilmenite.. ... . —---
+ 33 l1 66 -
— 3‘i

34,-‘47’3
34/473 Diepside—scapplite
Diopside-scapalite granulite,
granulite, Cherangai
Cherangai ya'llcy.
vaHey, three
three miles
miles west
west cf
'Of
Kapsiliat.
Kapsiliat.
34.5499
34/499 l-lernblende granulite,
HQrnblende granulite, western
western slnpcs
slQpes Elf Chemurel-tei.
'OfChemurakai.
34,-" 33'
34/533 Dicpside gneiss,
Diapside gneiss, tWQmiles
two miles SSW.
SSW. 'OfChemurokai.
cl' Chemureltei.
Ln

34;" 46
34/546 Calcarecus amphibQlite,
amphibeiite. Sembeywa.
Sembeywa.
Lu

CalcareQus
345333
34/585 E-pidcnsite,
Epidasite, eastern
eastern slnpes
slopes pt Garamnsc.
'OfGaramasa.
34;"319I
34/519 Skarn: Geben
Skarn, Geben ya Mayctc.
ya MaYQtQ.
 .

22

[1'1] Pelitic
(b'j Refills
Fetitie Rocks

" sehists and

fla1'1111' s9hists
Dark flaggy'
Dark an<i para-gneisses, from eia1'
derived frem
para~gneisses deri1-'ed sediments are
clay sediments, readil1=
are rea'dily
weathered and
weathered suffer rapid
and suffer; eresien so
rapid erosion that. they
se 'that' tend to
they tend enl11 where
euterep only
te outcrop super—
1a'here super-
harder rocks
impesed harder
imposed reeks have assisted in
have assisted in protecting frem rapid
them from
preteeting them deeempesitien and
rapid decomposition and
This is
re.111e1-'al1 This
subsequent iI"moval.
subseq1,lent illustrated in
elearl1r illustrated
is clearly the southern
in the 1l1'_.'i1e1_'a11gani hills
seuthern Cherai:J.gani'hills
where. seetieus of
visible sections
where visible 11E pelitic sehists are
pelitie schists leeated beneath
are located - elitts and
the cliffs
beneath the h‘111il's
and bluffs
termed by
formed mere resistant
1311 more quartzites and'
resistant quartzites para-11.neisses1 ,
and para-gneisses.

The best
The eeeur on
seetiens occur
best sections the western
en the stripes of
1western slopes Chemurelti at
el' Chemuroki 1111'
heiaht of
at height
between 7,600
between' T1t1t'1tl and i'eet. the
T1St'lt} feet,
and 7,800 estending southwards
espesures extending
the exposures Gel1en
tewards Geben
seLtth111-'ards towards
ya h'la1'ett'1.Furt11er
1—'a. Mayoto. espesures can
Further exposures ean be seen on
he seen the. upper
L111 the slepes of
upper slopes the
Garamese, the
et' Garamoso,
w.~stern slep es ~f
western slopes .
Saaetie and
et' Sagotio lariget. in
and Jariget, 111': valleys'
in the nerth of
1'alle11s north Hapse111 and
et' Kapserwa, and inIn
the _Meihen
the Moiben 1'i river.
'1'L- 1 " . ,

t"(i)
i '1 It:11111 1'11?— Gt"11"1'.1e t—B 1"11'1'1'1‘111: 511131
Kyanite-Garnet-Boitite Schists11' .1 1.11
K11anite and
Kyariite garnet are
and garnet are the minerals 'of
ehai'aeteristie ,minerals
the characteristic 111a111' of
et' many l1i1'11i1e—rf-L'h
the biotite-rich
el' the
schistS. tlutert'1ps on
sehists. Outcrops hillsides are
the hillsides
1111 the indieated by
are indicated talus of
b1-' talus Llarl'L'.erumhl1'1deep'11'-
L11" diuk, crumbly; deeply-
weathered rock
weathered reel-1 shedding hietite and
11h1L1n-L'i ant biotite
shedding abundant plates 'of
l_11'1ue-L1re11 plates
and blue-grey 1111111111:
k11a11ite over
et' kyanite the
surt'aees, The
hill surfaces,
hill The fresh' sehists are
11111L11111L1L'Ll schists
fresh unweathered seen in'
are seen in steep st1ea111-seetie11s
reek1' stream~sections
steep rocky
where the
where the. kyanite-bearing alternate. with
memhers alternate
k11anite-hearing members isletitie 'and
interstratifietl biotitic
with iritersttatified garneti-
and garneti-
parasgneisses.
t'erLrLts para-gneisses.
ferouS

In seeti1'111s.speein1ens
thin sections,
In thin specimens 34/501, 341515 (Fig.
L'1‘11-51'll 34/515 34.51213 from
and 34/526
51.11, and
{Fig.1. 5ib), t'ren'. the the
western sides
western sides of n1 111ur111111 Cit'.‘een ya
the Chemurokoi-Geben
111" the massit'1a11d
‘11-'la'1'ntn massif,-
11a Mayoto 351 Sill and
and 34/541 '.‘14 'itli.
and 34/584
tiren'i Garamoso,
from stun'tp; blades
Claran'iesLL stumpy blades of s1-'a11ite and
L11' kyanite and palepale pink p1 tilt garnet are set
aarnet are in a
set. in t'ehated
111 foliated
mesaie of
mosaic dark brown
1'11' dark hietite and
hr r1111- 11 biotite, and quartz '1'-1eeL1111pa11iee‘1 by
quartz accompanied ameunts of
small amounts
l1_1- small senehlastie
111' xenoblastic
eligeelase. The
oligoclase. k1'1-1itite. is
The kyanite suhidiemerp‘nie and
is subidiomorphic t'e:_'111s up
and forms L111 tote twenty per cent
twenty per cent of the
111' the
reel-1s.
rocks.

1__1=._1 Silliinanite-Garnet-IJiotite
511'.-11'1111'1111111-t1111'111-'.-.—}1’1'1'_11'11'e ,S<;hists...,
1511'1'11'11'1'
-""'1 11'". _ _- —. __ . .1 -- .
(ii)
Sillimanite is
Sillimanite is neither
neither well 11.'ell de'=ei1_1pe1l
developed nor 111117 conspicuous
1'111'1s1'1iL'111111s inin the rocks
the 1_'1_1elLs forming
t'-L'11':1'1i1'_=-'_1 the the
seuthern Cherangani
southern Cheran 1111i hills; 1"]-
L1.
1_ hills: it it often
when occurs,11eeu1's. however,
ht'111'e'1-er1 in in the
the. pelitie schists
pelitic sehists and and is is
distinguished in
distinguished t_‘.- utereps by
in outcrops h1=1he presenee of
the presence 111" white
white or 111' sill-ten
silken fibres in
fibres the foliation
in the 1'1_'-Ei.=_1';_i1'_:11.
planes.
planes~ - , , , ,

Specimen C111. ya
1'1'1'1'111'1 Geben
'1—l 5.31ti from
Specimen 34/536 “1111111111.euntains
1'11 Mayoto, contains minute111.111.11tepris111s
pri~ms of, sillirnanite
11’1' sillimanite
arrai'tgeti in
arranged in sheaf-like
sl1L1.1—l1lLe aggregates
1111111e111 es embedded
ernhedded in 11 aa fine-grained
tine-grained foliatedt'eliated matrixmatri' or 111'
dark brown
dark hietzte and
brewn biotite and quartz.quartz. In in specimen '4 tilf.“ from
speein'1en 34/615, twe miles
t'rL'1111 two 11e:'t1—l east of
miles north-east 1111'
Hapserwa, the
Kapserwa, siliimanite occurs
the sillimanite eeeurs in' in 'slender prism
slendei' prisms, rather fibres. and
than fibres,
rather than. and is is
aeeempanied by
acco'nfpanied garnet and
l_11-' garnet hietite. In
and biotite. ln each 111' these
eaL'h of esaniples the
these examples 111111111111
anal amount
the total
et" sillimanite
of sillirnanite does
dees not net. exceed
eseeed two 11111 or111' three
three per.
per cent.
eeni.

t'_ i i ll Kyanite-Sillimanite-Biotite
(iii) K_1.'11111.1"1‘1'1—51'1‘1’ 1'11 1 White-B 5111111" 11' Schists
511151 1".11‘1'
K1'anite and'
Kyanite and silli11'1a11i1e
' sillimanite eeenr t1111ether with
occur together l_1.ietite in
with bIotIte in spaL"-111e-'1s Still .11111.
specimens 34'/5051:rom a; 1 r- 1-1-11'1

|[iehen ya
Geben 1-'a Mayoto,
h'la1'L1tL1. and and 34/617
351_.'t1[?t"'11n'1
from aa locality
ieeali11'ttthree
hree miles
miles nerth—11'est
north-west
,
e'l" F1111gLetie.,
of Sagotio.

{11"} Gni'tteli'fernits' 51151 hits

(iv) Garnetiferous Schists - " " .,
The k11anite and
The kyanite sillimanite sehists
and sillimanite schists are
are i11te r-l'iedded wIth'
inter-bedded with garnetiferouS
aarnetii'ereus "schists
sehists
eentaining
containing none 1'isihle
visible a‘Lumine—silieates; they are
alumino-silicates; they are geiet'all11marlqed
generally marked 'byl_11' a11 eearser grain.
coarser'-grain,
and
and eentain less bietite.
contain less biotite, butbut are
are mere
more t'elspathie
felspathic. ' "" ~

,;ill ,~ ~-~-
"

l’lute I-(a)
Plate l—HH Selby
Hell);- Falls,
FHHH, six
xix miles
miles WNW.
“3“] {If Eldnrei. At
of Eldoret. At this
this point
puint the
[he Sosiani
Hmieini
rher plnnges
river plunges from
fmm thethe Uasin
Lflfiill Gishu
Gifihu plateau
plateau phonolites
plmnrrliteh onto
unln
fuel-H ut' the BHHEIHEHI H}
rocks of the Basement System. Hem.

{In'l'he
(b) The Hergnit riter. Eve-ten
Sergoit river, mile- emcl
seven miles east Hf
of Hny.
Soy. 'l'lle falls: at
The falls at 'H'el'fi
Nel's
Bridge “here
Bridge the river
where the riwer deneendu frnm phonolite
descends from phunnlite to
In gneih‘aee [if a
gneisses of H
Hmement System
Basement Hyfitem biller.
inlier.

...
 lI—{;£}Sergnit
Plan.- II-(a)
Plate Sergoit Rock (IHTG feet),
Huck (7,870 strip of
Imrnm strip
1144:“. a1-1 narrow System
Hun-Lennard System
111' Basement
HHFI’UUIIdL‘EI by
uni-ham: surrounded
gneisses plhzrnu'nlite.
h} phonolite.

1%..»

:hjfitlulut
(b) Ndalat (7,306 mimwd from
feet: viewed
[Lillfi feet) Eml. The
1111-.- east.
frum the ridge.
[lira-mm ridge,
The distant
three miles
5mm: three
some in length,
miles in cunumwe-‘J of
in; composed
length is ulnphihnlim.
nf amphibolite.

r-'
 "I"

,.

..

Plate III-(a)
Plate III—lai'l'hc suuthL-rn Cherangani
The southern ("hurunguni foothills
I'mnhilh viewed
xiii-“Ed from
frmn the
the south-east.
mum-£351.
Gurunanm‘r {H.942
Garamoso I'EIJH in
(8,942 feet) in conlrr.
centre.

) *9: 55:? ., 1.”?- fi-fii . : Th .

HHThI: Hindu: plain,

(b) The Kitale plain. looking
lnuking west “er-.1 from
fmm {'IIEmurukni
Chemurokoi [9.5.43 feet).
(9,548 feet}.
]-'I:Jgg_r. Inn-dipping
Flaggy, low-dipping qunl'tlitea
quartzites in iu the right t'-:_:rt-grnund.
the right foreground. :1
A Plflifi-
Pleis-
tncune hull! fluently;
tocene fault extends fmm from leftleft furugruund
foregronnd inn; ”valley
into valley in middle
in middle
(finance.
distance. Ht. Elgon
Mt. lflgnn {l—‘LITH
(14,178 flfl'l’l
feet) anan extinct
extinct unimm}
volcano in left
left
Initkgmund.
background, distance
distance fifl rnilur-c.
60 miles.

IP'
 Plate IV-(a)
Plate I‘r'—l:ll Soysambu
Enganumhu (6,340
[fiJ-IIJ feet).
I'EHI. Typical
'1'}piu1i massive
[nu-main: granodiorite
unmndinrile nf
of thr 111t
tbe Turbo
area.
area.

[Lu Biotite-amphibolite
(b) Bimitt-umphihniite agmatite
anmalile in
in grunudiuritic
granodioritic Illigmutim. Turbo.
migmatite. Turhn.

....
L
 r

Plait- V-(a)
Plate Y—Ia} Meta-conglomerate
Hela-cuuglnmerute in
in the
[he Tenten
TL-nten valley,
tuna}. three miles
miles; north-west
lmrth-uefl of

F":
I}
532mm.
Sagotio.

EhIHiacl-i
(b) Black flint}
flinty nu'innitu
mylonite nl'
of shuilnn
shallow din. une
dip, one mile north-east
mile [lnrtllvflflfii ul'
of
Huhnrnuu.
Kokorowa.

.. ..,.
~

l’lule VI-{a)
Plate ‘hI—hlliherlurnetl mirlnr fultl
Overturned minor fold inin alternating
alternating thin
thin quur'uiteh und biotite
quartzites and hinlile
gneiweh. t'ntlr
gneisses, milen SSW.
four miles “4511'. nt' Knjniliul- {'LiITIerLL
of Kapsiliat. Camera face}. nnrfll.
faces north.

1hll'he1'turner1
(b) intermediate fold
Overturned intermediate I'uld in
in muscovite
l'i'tClHiIl’: quartzite,
qu-uririie. three miles
mile;
muth
south ul'
of Fhenmrnkni.
Chemurokoi. {'umem
Camera fueey nnrlh-enwt.
faces north-east.
 ,

I'late VII--{a)
Plate Ell—taillinur
Minor t'nltl-s
folds inin ealeareerus liara—gneimex. (irellen
calcareous para-gneisses, Geben ya ta Mayoto.
Hayntn.
Camera faces
Camera rmrlh.
faeew north.

Hit
(b) Uterturaetl
Overturned intermediate fold
intermediate t'nld in
in veined
teineti ealearenm parargneififiefi.
calcareous para-gneisses,
fiehen
Geben 3:1 Haunt”. B-lineation
ya Mayoto. IE—lineatinn tparallel
(parallel tn
to hammer
hammer handle:
handle) inin
fluted erenulatinm
fluted crenulations at hinge of
at hinge nl' syncline
fineline nn on left. [Iamera faces
left. Camera faces
NEE.
NNE.

... -
~ -- -- --

Plate VIII-(a)
Plate 1'Ir'lII—ia} Dip
[lip 1Hal:-
slab u'jrl' era} eataelznite
of grey 1elith lineations
cataclasite with lineatinns' parallel
parallel to
in u‘.
a, tun
two
mile: sonth
miles Hflllil'l of
nf Kabiemet.
Hahiemel. Hammer
Hammer head head lies
lies parallel
parallel to
h:- the
the
regiflnal Hirike.
regional strike, handle
handle and
and lineatinn
lineation dip
dip 4H
400 eastwards.
eastwards.

:' W_.ijflW—Wi '-

-
[hlf‘h‘lulliflm
(b) Mullions {If eastwards dip
of eastwards [lip with
with lineations
lilleatium parallel
parallel to
in a:a in
in
llirq-mne. two
thrust-zone, tun miles
miles: math-east
south-east nf Hahiemet. Thin
of Kabiemet. hlaek
Thin black
nu'lnnite layers
mylonite Ia} era in
in left
left foreground.
l'nregrnund.

rl---
'-----
t

2'3
21

Specimen 34/504
Specimen 345504 from
from Gels-en
Geben ya ya Mayoto
T's-'tayoto is
is typical. It contains
typica.l. It contains pale-coloured
pale-coloured
garnets
garnets inin aa. well-foliateti
well-foliated matrix
matrix inin which
which folia
[olia ofof granohlastic
granoblastic ouartx
quartz anti
and tie—ispar
felspar
alternate with
alternate with more.
more hiotitic layers. The
biotitic layers. The t'elspar
felspar content
content exceeds
exceeds that
that. of
o~ quartz.
quartz.

[1. .1 11.111111111111111
(v) Graphitic 51.111 1.11s
Schists
Thin graphic
Thin graphic schists
schists were recrnderl between
Were recorded hctwccn Chemurokoi
['henturokoi antiand ILiaraiuoso
Garamoso at at aa
height. of
height of aboutabout 8.5131}
8,500 feet: they also
feet; they also outcrop
outcrop on the southern
on the southern extension
extension of of the
the
Sct‘t1l1c1.-'1.-I.-'a
Sembeywa ridge ridge about.
about twotwo miles
miles north-west
north-west o't' Kapsiliat. The
of Kapsiliat. The (jaranioso graphitic
Garamoso graphitic
schist
schist tspecimen
(specimen 34.514131.
34/542), is is aa garnetiterous
garnetiferous hiotite
biotite schist
schist with
with intcrt'oliatecl
interfoliated flakes
flakes oi"
of
graphite.
graphite, white while the
the Semhcgwa
Sembeywa outcrops
outcrops arc
are of of gt‘121.’
grey or or pink
pink telspathic
felspathic schists
schists tspccintcn
(specimen
11.141. ..ont.1n11.11
34/554), containing onlI.-' rare biotite
only rare hiotite in
in .1111.
'1iti=on to
addition t'o graphite.
graohite. The
The graphite
graphite constitutes
constitutes
ahotn
about HC's'Tll'l per cent of
seven. percent of the. root.
the rock.

(vi) F1111.p.'.'11—P111'111'1'1'1'11
Felspar-Porphyroblast 11111.1 1 It31' 11 ei.s.|.'e'.1'.'
Gneisses .

Itifit‘ll1111'it1it': peotic
Identifiable pelitic schists
'|.'
schists such such as as' those
those alreatijs'
already descrihetl.
described, are are sometimes
sometimes inc:- inter-
stratified
stratified with with 1.1.11.1.
dark 11iotitc-rich
biotite-rich t'oclts rocks. inactcmade conspicuous
conspicuous 111.1 by large
large white.
white plagiociase
plagioclase
porphs'rohlasts
porphyroblasts sometimes
sometimes measuring measuring one one oror twotwo ccntintctrcs
centimetres in in length Specimen
length. Specimen
34.713113
34/573 (Fig. 5c}. from
(Fig. 5c), front aa. deep deep va:lleyValley" between hetw'een Jariget
J'ariget. and
and Garamoso,
{'iaran'ioso is is representative
representat; Ire.
of this group.
of this group. In In thin
thin section
section tie the containeti tie spar. icien'.
contained felspar, ifierl as
identified as c1111....1s1.
oligoclase, is is oi of .1a
strongly ptirphyrohiastic habit,
strongly porphyroblastic habit. and and constitutes ahout sixty
constitutes about sixty per per cent
cent. 11.of11. the
the Jock; rock:
ouartz.
quartz, par.tIypartly granulitixctl
granulitized with with strain-shadows,
strain-shadows, hiotite biotite and
and ntinor
minor amounts
amounts oii of siEli—
silli-
mantc. muscovite,
manite, inttscosite. iron iron ore.ore and and apatiteapatite make make up up the rctnainclcr. The
ttJ.e remainder. The biotite
hiotite is is .'.'.t'ten
often
1.11.1.1.“ art_1L1nt;1
foliated around 111c1eist1at porph'_-.'t‘1'.1t_11'.?1:si.s which
the felspar porphyroblasts which have
haze 1:1-1111111111. 111111.111 by
evidently grown 1.11.! replacement.
I‘c-.11'.-'..:.c1.1'.

J 1.
, (c) Semi-Pelitic
5111:1111- 133111—111? Rocks
111.131.11.11.
-
Rocks derived
Rocks clccit'ccl from
1ron1 settintei'tzs: Jn1c111.1._.11 to in
sediments intermediate. composition between
in composition hei'1.-.ee11 mudstones
11'11111st.'-1.1-es
1111.1 pure
and pore sant1stoncs
sandstones are usually greyflaggy
are usually grej; .'taggjr gneisses gneis es containing
containing less less biotite
hiotite than
than the tte
Specin'tens 34/560
sc.1ists. SpeCimens
l1eiitic schists:
pelitic 34 211313 from1.1121111 between {Lhehntroltoi and
het'-.1.-'cen Chemurokoi tiiaramoso. and
anti Garamoso, 3—1 5.74
and ;34/574
111.1111 about
from about one mile east
one mile east of (iiaran1._1s-.1 are
of Garainoso at‘c typical
1315.31 of .211 the
the. group;
g1"..11t tltc.‘
they are 11.11111 grey
are. both g:‘c__
111e.1iu_rn—gt‘ainc-c1 biotite
medium-grained biotite gneisses.
gneisses. In in thin
thin sections
sections the 1111 11iotitc
biotite.. flakes
flakes are are small
srnal. and and
cons '.itute. only
constitute only a.. few
.t'ew perper t':e1.-t
cent of .11 the 1'1.'.1=.."1.. the
the rock, the remainder
retaincicr being heing composedcoon-sen of oi" a
foh|ate11 mosaic
foliated mosaic ot of 1.11.1.211'
quartz, 111. .1111: .c 1.1.11.1...1st. anti
albite-oligoclase :1".iert'1c1ine in
and microcline in appro s1nnatcls' count
approximaielyequal
1" .CIPDE'i lfiIlS.
proportions. .
Some of
Some 1111' the
.hc semi-pelitic
sen'ti-pclitio rocks.'ocxs contain
contain very 1.1.1. small
1.111111! amounts
amounts of -.'_':-1 sillimanite
siliinntnitc or .11:
1.1111111 .1. as
kyanite, 11s in111s1'.1ec.=.111en
specimen 34/514, 34_":'1|4. a.'. pale
pale grey
gt'e}-'fIgs1.' gneiss from
flaggy gneiss from thethe eastern~af).k
et'tstern fianl. of 111'
Lichen ya
Geben js-'a Mayoto.
l‘s-"11'13c‘11o. In
1n thinthin section
section thisthis roc.\<
rock isis seell
seen ~oto contain
contain biptite
hiotitc and .tntl muscovite
11'111sco'1'ite
in a.pproximately
in apr11't'1xin'1atcl1.-' equal c1111...11 proportions
proportions set set in
in aa foliatedquartz"microCiine
toliatetl t111a1't'x—ntic:_'.:.ciinc matrixmatrix. together
togctn
with a few srnail slender post of siltitnanite
with a fe'Y ,small slender prisms of sillimanite.
Specimen '.1—1111121.
Specimen 34f618, is is aa deli-ca te.[1.-.|arninatcti
delicately gnciss from
laminated' gneiss front thethe foothills
foothills of
ot' the
the
Che. a'ngat'ii hiils
Cherangani alitnlt. four
hills about four milesntiics north-west
..o..nwest of of Kapserwa.
Hapserwa. In 111 thin
thin section strongly
section strongly
alignedtti:1otite
aligned biotite with with thin
thin J'oliarioos
foliations o._'of itmenitc
ilmeni1e and large cr1.-'sta1s
and large crystals ot'of snhcnic
sphene areare seen
seen inin
aa fine~grained
1111c—er.11.1n1.11.1 1'oliatec1
s.
11'11'1-saic of
foli~ted mosaic ot "quartz,
otxtrtx. albite-oligoclase
alhitc—oiigociase andattcl microcline.
11'1icroc lino

l'
!
., I'.'._] Psr.1111111'11
(d) Psamm(tlc .11?r1c.|1.1'
Rocks
\
The metamorphic
The metamorphic equivalents
equis-alents of pure quartz
of pure quartz arenites
arcnites and felspathicsandstones
and t'elspathie sandstones
usually form
usua~ly t'ornt massive,
Inassis'c. 'reSistant,
resistant. and
and extensive
extensive outcrops;
outcrops: in consequence
in consequence theythe}; are
are
t'ountt in
found in cliffs
Hills and.
and crags
crags atat the
the crests
crests ot' ridges and
of ridges and onon the
the summits
suinmitsof of many
many of .11
the highest
the hills-
hiuhe st hills.
L ; ---

24
-
til Quartzites
(i) Qtturtzites' and
tutti Muscovite
.Mtts'eot-‘ite Quartzites
Qttt‘trtzitex
reddish—brown or
h-‘lassiye reddish-brown
Massive grey—weathering quat'tzites
or grey-weathering quartzites outcrop t'iyet' wide
outcrop over areas:
1wide areas;
they make
they make the the hill
hill feature
feature ofof Karuna
Karena {"1693 feet}. and
(7,693 feet), and extend
extend northwards
northwards along
along
the high
the high ridge
ri ‘ge of
ot Kapsiliat
Rapsiliat (8,539
£3539 feet)
feet] to
to Kapsigoria
liapsigoria andand Kuserua
Ruset‘ua (9,200
Willi} feet),
feet}. in
in
the extreme
the extreme north-eastern
north-eastern corner
corner ofof the
the area.
area. Similar
Similar quartzites
quartzites are
are extensively
extensiyely exposed
exposed
in the
in the Chemurokoi
Chemurokoi foresti‘orest reserve,
reserye and many of
and many of the
the. small
small hills
hills between
between Chebororua
Chcbororua and and
the 'lxzeia
the riyer are
Nzoia river are minor
minor features
features caused
caused by by the presence of
the presence relatixely resistant
of relatively resistant
bands of
bands of quartzite
quartzite in in the
the metamorphic
metamorphic succession.
succes.:ien.

Quartzite is
Quartzite is seen
seen to
to the
the almost
almost total
total exclusion
exclusion ofof other
other rock
rock types
types inin the
the
(Themtirtihtii-Kaistitigttl region
Chemurokoi-Kaisongul region titnewn locally as
(known locally as ”Flat Top"__]. where
"Flat Top"), where outcrops
outcrops
extending northwards
extending northwards outside
outside the
the area coy-er several
area cover scyeral square
square miles.
miles. The
The surface
surface extent
extent
in this
in this part
part ofof the
the Cherangani
Cherangani hills
hills does
does not. however, imply
not, however, imply anan excessiye thie‘sness
excessive thickness
tor the
for the quartzite beds since
quartzite beds since the regional dip
the regional is low
dip is low and the topography
and the topography is is dominated
dominated
by great
by great dip-slopes
dip—slopes coincident
coincident with
with the
the gently inclined quartzite
gently inclined sheets.
quartzite sheets.
Typically the
Typically the quartzites
quartzites are are white
white a~dand translucent
translucent on on fracture
fracture surfaces,
surfaces. with
with
quartz gr;iins
quartz grains reaching
reaching aa size size ofof 5
5 mm.min. oror more
more in in the
the coarsest
coarsest varieties.
yarieties. Finer-
Finer—
grained, museoyite—quartzites are
weil-t‘oliated muscovite-quartzites
grained. well-foliated interbeddcd with
are interbedded the massive
with the layers.
massiye layers,
and sometimes
and contain small
sometimes contain grains of
small grains kyanite. as
of kyanite, as in specimen 34,-”532
in specimen from one
34/532 from one
mile north-west of
mile north-west Chebororua. In
of Chebororua. In the vicinity of
the vicinity of Chemurokoi lenses and
Chemurokoi lenses sheets of
and sheets of
tough. green,
a tough, green. quartz-diopside
quartz—diepside granulite
granulite areare sometimes
sometimes enclosed
enclosed inin the
the quartzites,
quartzitcs.
and occasional
and t‘ieeasional prisms
prisms of oi" colourless
colourless diopside occur in
diopside occur in anan otherwise
otherwise pure
pure quartz
quartz rock,
rock.
as in specimen
as in from the
3-if—‘lSl from
specimen 34/481 foothills one
the foothills one mile east of
mile east Ciehen ya
of Geben May-'oto. It
ya Mayoto. is
It is
clear from the
clear from presence of
the presence litt'ie—silieate inclusions
these lime-silicate
of these tle original
that the
inclusions that arcnitcs
original arenites
contained thin
contained thin beds
beds of of calcareous
calcareous sand.
sand.

lit) Quartz
(ii) Feelspur Para-Granulites
Quart: Fe/spar Pt't‘.i‘t'i'-{?!IE"t:.H'_i'E’.i'
uttrtr Para-Gneisses
Ptti'rt-(i’i'uutiilitex' and
Felspathie gneisses
Felspathic gneisses and
and granulites
granulites belieycd
believed to to have
have been
been deriyed
derived from
from impure
impure
sandstones or
sandstones or grits
grits constitute
constitute an extensiye group
an extensive group in in the
the meta-sedimentary
meta-sedimentary succession.
succession. A
Pt
regular
regular foliation, granular texture.
foliation, granular texture, and
and interstratification
interstratification with
with rocks
rocks of
of undoubted
undoubted
sedimentary origin
sedimentary origin imply
imply that
that they represent original
they represent original arenaceous
arenaceous sediments.
sediments.
These rocks
These rocks areare very
yery well
is ell exposed
exposed in in the
the cliffs
elit immediately
immediately east east ofof Chebororua-
Chebororua,
where massive,
where massiye. brown-weathering,
brow-'n-weathering. weakly weakly foliated
foliated gneisses
gneisses andand granulites occupy
granulites occupy
set-eral hundred
several hundred feet feet. of of the
the visible
yisible section.
section. Specimen
Specimen 34/523
3-1523 fromfrom thisthis locality,
locality.
contains about
contains about 25 25 perper centcent ofof quartz
quartz some
some of or which
which is is poikilitically
poiltilitically enclosed
enclosed in in
replaciye crystalloblastic
replacive crystalloblastic oligoclase.
oligoclase. Microcline
Microeline and and orthoclase
orthoelase are are also
also present
present in in
lesser amounts,
lesser amounts. and and dark brown biotite
dark brown biotite is
is sparsely
sparsely scattered
scattered throughout
throughout the the rock.
roclt.
Specimens 34/474
Specimens '34 411 and and 34/494
34 49—1 areare. similar
similar inin composition
composition and texture. the
and texture, the former
former is is
typical of
typical of aa pink
pink foliated
ft'iiiated para-gneiss
para—gneiss forming
forming the spine of
the spine of thethe ridge known as
ridge known as
Sembeywa. some
Sembeywa, three miles
some three miles north-west
north-west of of Kapsiliat. whilst specimen
Kapsiliat, whilst specimen 3-1494.
34/494, waswas
taken from
taken from thethe cliffs
cliffs ofof pink
pink para-gneiss
pat'awgneiss between
between thethe Moiben
h-Toiben gorge
gorge andand thethe Karuna-
Karuna—
Chebara road.
Chebara road.

A distinctive
A para—gneiss appears
biotitic para-gneiss
distinctive biotitic appears in exposures in
scattered exposures
itt scattered in the Tenten
the Tenren
region. about
region, about five
the miles
miles north-east
north-east. of
of Kapserwa.
Kapserwa. It It is
is dark
dark grey
grey in
in colour
colour and
and of
of
medium grain
medium grain apart
apart from numerous rounded
from numerous rounded or or ovoid
oyoid quartz
quartz inclusions,
inclusions. measuring
nteasuring up
up
to two
to two inches
inches in in diameter. which are
diameter, which are arranged
arranged in in banded
banded concenm-ations
concentrations resembling
resembling
graded pebble
graded pebble beds
beds inin aa conglomerate
conglomerate (Plate
(plare V, V. a).
at. The
The matrix
matrix inin which
which these
these
"pebbles” are
"pebbles" enclosed is
are enclosed is granoblastic
granoblastic and
and biotitic;
biotitic; specimens
specimens 34/598
34, 598 and
and 34/616,
34,616. both
both
from aa deep
from valley situated
deep valley immediately to
situated immediately the east
to the east of Tenten. contain
of Tenten, and
quartz and
contain quartz
oligoclase
oligoclase in approximately equal
in approximately proportions togethe'
equal proportions together with microcline. deep
with microcline, brown
deep brown
biotite- and
biotite, sphene.
and sphene.
 25

[
I

0 2
L Jmm.

(a)
(a) (i?)
(b) (‘3)
(c)
Fig.1.. S—llisrussups
Fig. 5-Microscope drawings of
drawings 11f thin
thin ssctinns
sections of of metamorphosed
mstumnrphussd sedimentary
ssdimsnmr}
rs-sks
rocks frsm ths southern
from the southern Chsrsngsni Hills :—
Cherangani HiIls:-
{s} Diopside
(a) Spssimsn 34/533,
gnsiss. Specimen
llispsids gneiss. frsm two
34-533, from {as miles SSW. of
111ilss SSW. 11f (Thsmu-
Chemu-
rnkni.
rokoi. flrdinurs‘ light, X
Ordinary light, In: 13.
I3. Quartz
Quart! {Q}, l’lagiflslass (P),
(Q), Plagioclase (Pl, Diopside
Uinpsids
:Dl-
(D), Ssapulits
Scapolite {Sc},
(Sc), Epiduls
Epidote {E}, Sphsns {'51.
(E), Sphene (S).
H11 Kyanite-garnet
(b) Spssinisn 34/515,
sshist. Specimen
Esanits-gsrns: schist. frsm the
34 5.15. from ths western slupss sf
nests-m slopes of
Chsmurnkni.
Chemurokoi. flrriinury light. x 13.
Ordinary light, 13. Kyanite
Eyanits (K),{K}. Garnet
Garnst (GI.
(G),
Bintils (8).
Biotite (Bi.
{Cl Fslspa‘r porphyroblast
(c) Felspar porphyrflhlast gneiss. gnsiSs. Spssimsn 34/573,
Specimen 34,9573. fmm Jariget.
from Jurigsl.
Drdinars‘ light,
Ordinary light... X1-: 13.
13. Quart:
Quartz (Q),I'Q'}, Plagioclase
Plagiuclase (P),(Pl. Biotite
Bifllile (Bl-
(B).
Ths sL1111psisitis11sl
The compositional rungs of
range :11' the
111s pelitic,
psliiis- semi-pelitic
ssmi—psiiris 111111 pssmniiiis metamorphosed
and psammitic n1si11n111rpi11'1ssd
-ss:li:11sr11s
sediments is is briefly
'rsrisfis' i111lis:1:sd bsisss':
indicated below:-

.1415 1 s
34/515 14:04
34/504 s4, 51.1
34/573 34,560
34/560 345:1:
34/532 141494
34/494
-_ . —|_ -__ __1-___.__ -_ __,___
I

11 ,-
%
0-“
-' U
‘3'.
% "(.1 % U %.-"
U- % L] %'3'

Quart:
Quartz . . . . 2-5
25 30
30 35
25 -5
25 .
93 35
35
Misrsslins s1:
Microcline or
0:111ss111ss
orthoclase . . -— 2 -— l5
15 -— if}
10
l‘lsgisslsss
Plagioclase _ . 1,
20 36
36 151
61 54
54 -_ 5:)
50
Bistits
Biotite. .. .. 35
35 15
25 10
10 55 2E 33
Mussss’its
Muscovite . . -
— 33 2 — 33 1l
Clams:
Garnet. . . . . 33 33 -— — 2 —
Ks'1111i1s
Kyanite s11" or silli-
silli-
111:111i1s..
manite .. . l5
15 -
— 1l —- 22 —
1:11:11 111's
Iron ore , . . . 22 1l 11 l — l
Asstits ._
Apatite ._ I
-—-— -— + I — —

34,-“115
34/515 F'sEiIis kyanite-garnet
Pelitic ks-‘sniis— gsms: sshis:schist,.Ci1s11111mk11i.
Chemurokoi.
34"504
34/504 Ps Iitis gsmsiifsrsus sshis1
Pelitic garnetiferous schist, iiisbsn Geben ya 1:1 Mayoto.
31:11-11:11.
34"5TPsii1is tsispsr— p121
34/573 Pelitic felspar-porphyroblast rpinrsblsst gnsis .sJ igs:
gneiss, Jariget.
34/560 Semi-pelitic biotite gneiss, between Chemurokoi :111Li
1’1}
34'51'1'1 s
Ss mi-psl iiis bisiiis gnsiss, bslss'ssii Chsmursksi 6111111111131.
and Garamoso.
Psammitis muscovite
34,5532 Psammitic
34/532 Ssgstis
1111:11‘12its, Sagotio.
1111iss11s'its quartzite,
341' 49 4 Psammitic
34/494 Ps:1r11111itis quail:— isisss: para-gneiss,
quartz-felspar [1:11:1— ”nsiss three
[hiss milss
miles ESL
ESE. sf Kapsiliat.
of Kapsiliat.
IW -

2e}
26

Lit-1reLLLLLLLLL'pLi'tLIL'eLu-i i-L’L'LLLiL 'L'LLL t'e RL'LL'LELLL

Metamorphosed'Volcanic Rocks

{LL} Hornblende
(a) Ht‘irrthienrie {ELLLLL'LLLLL‘
Gneisses. LLLLLL.r sitirpiriiiLiirteL‘
and Amphibolites
Hernhiendie reeks derived frern
Hornblendic rocks derived from lavas or Ituffs ere iL'LL-L-LL er tLIttL diihetiit to
are difficult te dietingeiLh
distinguish fLeILi-Lfrom
.LiLrLiie-r rocks
similar rLLLiLL formed
fLLLLrieLi freer
from thethe metamorphism
nietLLeeLphiLLrt of Lif calcareous
eLLieLLLeeLLL sediments.
LediLnehtL. A .2‘L volcanic
L-‘eeieLLnie
erigin is
origin iL attributed
LLL‘trihLited heLL-eLLer
however, te to theLe L'Lntphiheiites which
those amphibolites LL hLLh LLre iLLLLe to
are found te possess
eLLLLeLL reiie relic
igneeLLL textures
igneous Lei-LL LireL or
LLr pyroxene,
pL- re-Lene. but
hut. lack
iLLeiL diopside,
Liiaide. and end carry
eLLLr} abundant
LLhLLndLLnt gLLrne'L.
garnet. \
Speeinten 34/522
Specimen 34,-"52’3. fromfrern below heiew the the cliffs
eiit'DfL-L' immediately
inLnreLiintLi'-' east LeLLt eif C'hehLLL‘Li-TLLLL. is
of Chebororua, iL aLL
tL'pieLLi eLLLLLLe—grLLiLLeLi gLLrLLet
typical coarse-grained entphiheiite. TiLe
garnet amphibolite. hernhiehde is
The hornblende LL aLL. deep pieeei .LeLe L-‘L—‘LrietL-z
deep pleochmic varieJty,
L-LeeeaL-Lnied by
accompanied iLL-L large
iLLLge LLhrtLL-ndine
almandine garnets garnet-L inin ea xenoblastic
.LLenebiLLLLLe matrix aLIrii-L of ef LLLLLieLiLIe.
andesine. QLLLLL'LLLQuartz is iLL
LLa rare
rLLre constitllent.
eLinLL-tittierit. Specimen-
Speeitnen 34/468 34546-3 fromfrerrt the :‘L'it'iii'ifl'tl river
the Moiben L'iL-er ene
one milerrLiie west
LL'eLt. ofet Chebara,
{—_hehLLL—LL.
iLLcomposed
is re
entaed einLeLtalmost entireiL-
entirely et' dark green
of dark hLirhhiende ind
green hornblende piLLgieeiLLLe in
and plagioclase iLL approximately
LLppL'L'LLLin'LLLteiL-'
eLLLLLLi prepertiens; the
equal proportions; the two minerals have tee LtiinerLLiL have aLL sub-ophitic
Leh-ephitie texture LeLL'tLLre :LLneL ..'Ling that
suggesting that the}:they
hL‘LL-‘L: recrystallized
have teIer'L-L'Lttiiiized from
i'rL'irrL L'a-1 basic
hL‘LLZLiL: igneous
ignetiLILL rock.
Leek. Relic Reiie igneous
ignet‘LtIL te"tures
texture-“LL LLr'e
are alsoLLILLLLI clearly
eie:Lri‘_L-'
LheL-L-h in
shown in aLL dark
Cittt‘h'. gLLrnet LLI'L'Lphiheiite etLterL'Lpping
garnet amphibolite outcropping at at thethe northern
Lierthern end end of ei' Geben
{Lie-hen ya j-E

:Ju'
‘L'iLLLLLLte- In
Mayoto. ILL thin Leetien L'Lpeeinten
thin section (specimen .i4..-’4L'Li‘L-"__i.
34/497), pale pale green
green LLLLeite-L-Lai hL— pLLLthLLLLL LLL
augite and hypersthene aree .Lseen
een
in an
in an advanced
Lid-L:Lneed stageLtL'Lge ofLit uralitization;
tLrLLiiL itt ien. the the. pyro'xene
pL-reLene and LLnL'i secondary
LLLLL LLLiLLrIL- hernniet
hornblendeLie is iLL usually
LLL'LLLL:'i}
pLLLLLtLLi from
separated treLh interstitial
iLLterL LitiLLi LL. LL-LLLLe hL:
andesine by gL-Lrtret
garnet coronas. eL'LrLinLLe.
U11 the
On the Kokorowa-Kapserwa
iLi'Lei-LeL‘eLLLLL-iL-LLpL-LLL'LLL'LL. ridge
riLige there
there. LL'e etL teLLLp-L of
are outcrops LLL LLa dense
LieILL-Le garnet
gLLInet L'amphibolite
LL LLphii. Lmiii 1e
LLLLL eirrren 34_'tit".i3.
specimen LLLLLLLLLILLLLrr g_LLrLet.L
34/603, containing garnets renehtnw reaiching the the size.L'i'LLe ofeLt' LLa gL'iL t- hLLL-i Ln
golf-ball, in LLa :rLLLtLiLL
matrix L'Lt of
L-L'LLge
larger intetiLLeI-Ling prisms
interlocking pLiLnLL of et' hornblende
iLnrnh-‘ende together tLigeiiLet with LLith scattered
LLLLLtLered granules
gLLLtt‘ieL of LL:T ironirLLn Lire.ore.
He LLrhjL. at
Nearby, the summ1t
at the :LLLnLLrLit of
(if Kapserwa
iLLLpLHLL'LL (trigonometrical
trigenLLnLeLrieni station Ltetinn 89/54),
HF} 54}- therethere are Lire. scattered
Le.LLtteIeLi
etttera of
outcrops ef L'aL diLtirIetiL-e. nreLiiLLtrL-greineLi garnetiferous
distinctive medium-grained geLrt‘Letit'ernLLL LLthihLLiitL-L.
amphibolite containing eL::.t'-Li:1"ng LLhLLnLi-
abund-
tt garnets
ant garnets LLnLi and L'riLLLL—L
yeliow~brown reL'LL'n cummingtonite
eLInLLtLiL-LgLLLn-ite in in LL.a .foliated
feiiL-Lted 'granoblastic
gLLL nLieiLLLtie matrix Iti'L-"ti-TiFL Lit'
of
LLnLieL-L'i he. specimen
andesine, Lpeeinren 34/604.34' t'itIL-i Itit. is
iLL likely
iii-LeiL-' that
thLL'. both
hL‘Lth ofLIFE these
thee-e examples
e:-:;LI.-L;.ieL were
LLere derived
Lie. i-LeL'i t'rnnt from
ignenLL L rLieiLL.
igneous rocks.
[iii Biotite-Hornblende
(b) B-LLL‘ILL—L’L’LJLL iLL’LLLL'LiLL {Li"LLLLI".L..L'L-L.L'
Gneisses
'[JLLriL banded
Dark handed hornblendic
hernhiendie .gneisses
gneiLLeL caneLLn be he traced
trtLeed fOT
iLL-r several
LeL'ertLi milesLLLiieL parallel
pLLL-LLiiei to
LLL thethe
upper reaches
upper reLLeheL of'e-f the
the ILL-inihen
Moib~ river riLer near
tier-LL Chebara.
IIheLhere. in LpeLeitnen 34/488,
In specimen 34:433. fair-n thL e
from three
mite LL SS‘L}
miles ssw. of I‘LhehLL
Chebara, .hL-LLLhieLLLie
hornblende and LLLLLi biotite
hiL'LtiL-L: constitute
eLinLtitLLte about
L-‘LiiL'r-et one-third
LinL-—tiLi: d of LLI_ the
the rock,
LL Li:-
the remainder
the rer‘LtLLinLieL‘ consisting
eenLiLtiLig of Lit-E xenoblastic
LettehiLLLLie calcic
eLLieie oligoclase
niig LiLLLL L-LeL LL'LLLLLLrLiLL by
alccompanied i..-L- less
ie LL than
then fivethe
per eenL
per cent Lit" LpLLLrtLL. LLnL'i
of quaTtz, and L'LeeL-LLLLLLL
accessory LL|::LL-Ltite.
apatite. '.

t4} TLEFFTMhiiiH HLLL'LLI AND

(4) METAMORPHISM .L‘Lti L’L'i'rL-LLLLI'rLILitLL:_;-:L
GRANITIZATION '
The Lee-LL Lit" the BLLLenient
The rocks of the Basement System have achieved their SLLtent h-L-‘LL' L - :LehieL'eLi their presentpreLeI‘LtLcomposition
.:=:L;It .L-Lit: LL.L Lin-1L:
only
after the
after the completion
eLLIhp-‘etinn of Lii‘ aLL complex
eerie-pie); LerieLL
series of Lii.’ transformations
transfer'LnL-LLiLLLL-L involving
iIrL'L'LIL'ihg recrystallization
reeLLL.LLi;iL'-.L-Ltinn
end the
and the development
deL'ei Linnie.Lrt of nf newrLL LL minerals
hLL nerLLiL under
LLLLL ier changing
Lilt-Z‘Igiiig conditions
e-LinditiLLnL of et' tempe'ratun~
LL'LLtz-pr-LLLLLLIre andan d
L..T:'1iLL§i[iI'=:'-‘.i]i
pressure. eLLnLiLieIihg these
In considering LheLe changes
ehLLLLgeL the LiLLinetien between
the distinction he‘s-seen the Lhe. migmatites
mien; ‘L and
'_.L.

g: L-LLLL‘LLiiLiriL eL of
granodioTites ef -thethe Turbo
'i'LLL‘hLL :L:‘eLL
area and LLLLLi the
the metasedimentary
Ine.L.:L.LedinieI'LtLLrL' rocks LL of hi thethe II_.L:;eLLLng.'1LiL
Cherangarii
hiiis is
hills iLL maintained
IL'LLLLILLLLnLeI for Lnr deLerIpLLL pLIrpeLeL.
descriptive purposes.
trtt Metamorphism
(a) ifLLtLL'rt-LLLLLLLLLLLL and
LLLLLL' {LL LIILt'”LL".LLL of
Granitization elf the
L‘L’L'L-L Turbo
L'LL'LLLI Area
-.-'f.-"L-‘L'L'
C'eLLtL-LLLL
Contrast between hetLLeen geosynclinal
-geeLLnL'-.-‘inei LLeeLInLLIiLLtL'LLL-LL
accumulations and :LnL'i the
Lite. tiLLLLr
floor er. LLhieh they
on which they Lire are
LieaiteLi is
deposited izL liable
iLL-'Lhie to
tLL be
he aLL fundamental
fLILLdLLnLerIt-LLi feature
feature in in those
tiILLLe areas
LireLLL where
LLhe Le linear
i_ineL-Lr .subsidence
LLLIL-LLLidenLe
Lind sedimentation
and LedinrentLL‘LieLL has hLLL taken
LLLi-L'en place,
piLLee- Linee
since more rrLLLL'e often
eLLLL-LL thanthLLn not net in
in the
the gL LLiLiLTLL..i record,
geological Leeerd
the foundation
feLILL'”L-LLiL.'Ln has hLLL ptLLLed LhrLLLLgh at
ILL-Ia,

the passed thTough LLt least

ieLLLLL oneLine earlier
eLLLiiet cycle eLeie Lir- .netenterphiLnL and
of metamOTphism LLnL.
grLLnitiLLLLLien
granitization and end in in L'LLnLeLLpenee
consequence is iLL liable
iiebie to te be
be grenitie
granitic in eenreeLitinn. With
in composition. ‘IL'IL-"ith the
the meetonset
nf the
of the new
new orogenyLLrLLgenjL= bothheth foundation
tLLLLneiLLtien and Lind superincumbent
LLLpL rinettirihertt sediments LeLiinLeetL Lire
are LLtL subjected eted te to
intenLe grLLnitieetiLLIL in the LieLL'LLtlLLnging LeetienL Lif the geeLL.:Leiine LLLL thLLt erigihLLJ
intense granitization in the downplunging sections of the geosyncline so that original
LiifiiereneeL ere
differences eliminated, and
are eliminated, and whenLLhen :these
theLLe crustal
erLLLtLLi zones
zLiLLeL are revealed in
are revea:led in thethe migmatite
rnignretite
LLreLLL of
areas ef Preca:mbrian
iJreeLLnihriLLn terrain,terrein. it it is
iLL often
Liften impossible
intpeLLihie to' tLL distinguish
LiiL‘LingLLiLh between
hetLLeen renLehiiiL-Led
remobilized
deer and
floor and granitized
grLLrLitiLLeLi cover.
Lever. In in the
the regr,ons
regiene marginal
trierginLLi to tn thethe deep
deep grenitieetinn
granitization' zone, 'LrL'Lne.
hL_LLL=eL'e1‘. cover
however, L‘L‘IL-‘er and
and floor
finer have
hLLL'e notnot been
been intermingled
ihterr‘ttirigieti and :LnLi welded
weided together
tngethet‘ to in the the sameL'LLLI'ne.
 :11?
Z7
degree. and
degree, attd are
are sometimes
se1t1etin1es recognizable
recognizable assepaTate
as separate orustalentities;
erttstal entities: such
stteh is
is the
the relation-
relatien—
ship between
ship between thethe migmatites
111ig1natites and
and granodiorites
granedierites of
e[ the
the 'Tttrhe area and
TUl'bo area anti the
the metamorc
rnetatner-
phesed sedintentar3' cover
phosedsedimentary ee3'er ef the 1Cherangani
of the hiils.
Cherangani hills. .
. .
The present
The present. granitic granitie charactereharaeter of 11[ the T'ttrhe r()cks
the Turbo reeks is is considered
eettsitiereti to' te be he attributable
attrihntahie
111 two
to t33'e separate
separate orogenic eregenie events, e3-'ents_._ tirstl3-'
firstly an an earlier
eat'iier cycle e3'ele of 111'. high
high level level granite granite intrusion,intrttsien.
and
and seeendi31
secondly aa ntetasentatie metasomatic granitittatien granitization 11ee11111part31ing
accompanying penetrati3'e penetrative deformation Liet'ert'natien er' of the the
t'eLtndatien during
foundation during the the folding
feitiing and anti metamorphism
111et11111e1'phis111 of 111' its
its stiperinettn'thent
superincumbent rocks. reeits. That That the the
l1'1L11'1e'ati e11 was was an an Lssenttal31 hentegeneetts crystalline er31stalline. substratum s11i1stratttn'1 before het'ere the
.' foundation
tn" the latestiatest ereget13'
essentially homogeneous
is 11131111111311. net: 1113' its 1111'Lh11ieal
the inception
ineeptien
of the orogeny is demonstrated by its mechanical resistanee resistance to te def1'11'1111tti111th1tts
deformaition, thus
'13-'hi'1st the
whilst the covere113'er rDcks reelts were 331et'e folded
t'eided against against and and over rum it, the [he foundation
reL111L1-atien failed faiieti by 't.13' deep
deep
shearing under
shearing under direeted directed pressure. pressure. The The shear-z;ones,
shear—'1':_11'..-':s. '31'itit'h which dip dip generally
getterali31 eastwards e.:-1st1"311rds
beneath the
beneath the para-gneisses
11111'LL3LL'1L1111es 111.1tl and schists'-:-."i1.is1s of111' the
the southern
s-'L'.111thL'-.r11 Cherangani
{'ltet'anaani hills, hills. occupy nee-.1113: widths -..1.'itiths
111' 111'_ 1.133'
of many hundreds of itt1r'LlLL 111' feet
feet 11ndand h:-1L3'-::
have provided 111'113'ide1i 1111111111131:
avenues for !the :11: free
l'ree migration
ntigrLttien of 111' granitie-
granitiz-
ing:i1g fluids,
fittids. particularly
311r ".L'1:."i:'1:'l1.-' alkalis,
alitalis. which 31.'E1ie‘-1|i'1:11.-'e
have moved 111.1131eti upwards 11p33'ards and 1111133:1rds from
and 'Outwards tree: a:1 deep deep
asiai .tene
axial Zone 111' granitiiiatien to
of granitization re the the east. L111..'- These
'i'hese fluids fitiids became heL'arne fixed i'ised as 1'.-.'. replacive
1'e'-'L.'11L'113e 111iL'rL-
micro-
eline and
dine and sodic sedie plagioclase
piagieeiase in in the :he IDcallyI1e'll31 granulitized
granniitiaeel foundation. t'etntdatien. Compressive '.'L' 11.111.11L31L13L stress stress
eentintted to
continued 11:1 a1'1 late
iate stagestage and and was ass releasedreleased 113' by 1".11a'1 L. LLLL|13 -s and
final cataclasis :11ilii1'1g of
and milling 111' the
t'.1e rocks
r-1e'11s
1'11 thrusts
in 'Lhrttsts unaffected
ttnai't'ee'LeLi by l'13's11hs'21111e111
subsequent metasomatism. 111-L LL1.1_11..-11L11.s.-1'1_ Attention
.t-‘3 tenti1111 has has been heen drawn tira3-Lr1. to 111 the the
i1111_e.et't:1t1i function
important "11L'ti1.1:1 during t:'11'i11g e:'1"1g-L-11.3-
orogeny 11l' of deep e'p marginal
1'11L11'gi:'1.'1 l thrusting
thrusting 111' this kind
of this kind in in providing
presiding
.l're'e passages
free passages for 1'111' granitizing
gr:—11'.iLi:1'.ing finitlsfluids 1RL1111hez'g.
(Ramberg, 1952, 13152. p. 1:1.2.i.'.'._1.11111.'i
238), and that that metasomatism
111:11-1s1'11111111st11
reae'. eti an
reached an acmeaet'ne duringduring pro pretraeted
traded tiiti'erential
differential movement 111113"1.11'1e 111 in in ,the
the foundation,
1'11nt1=:i:-11';1111. cannot eanrtet be he
tietthteti from
doubted item the the textures
teatttres of '3'". the
the rocks reeks seen seen in in the tit-'1. TurboI'Ltrhe region. Lg1111 Under Under estre111e extreme
:11e as'L'11111ttisn'1. viscous
metasomatism, 3-'isL':111s microcIine
11'1ieree11e granite granite lenses.3lenses, veins, ein: . and anti sheets,
sheets. were 1et'e formed t'ernted in in the the
tht'11s1'—.111111-e.". and
thrust-zones, and itit is is pessihi'e
possible that that the the thermal
11"r1111'11 eiieets effects of el' 11.31t33'a:'
outward11' spreading spreading rheo~ rhee—
11111:'pi'1ie granite of
morphicgranite 11." this
this type t3'pe contributed
eet1tt'iht1.'ed t'O 11'1 the
the comparative
earn.'1'..1r1'1ti31e unifol'mity
ttnit'er 111it 3' of 111' metamorphic-
111et1'1n111r11hie-
grade in
grade in the 111111'L1li1111 meta-sediments,
the mantling 11'1et1-11se1ii111e:11s. implied i111.r_'1"Lietl by i:-3' thet..L' considerable
L11L1s11LL1-.L-L-1l_'1-L breadth breadth of 11l' both
heth
the kyanite
the i13-';1ni1e and si.='-|it1'.:111it1:. terms
and sillimanite zones as as at at present
present defined defined (Sanders, t'fiianders, 1954 11.1.14 B, B. p. p. 150). l::'11"1'1.
.1‘3'111'11' termination
Abrupt te1'111inati1'1r1 of 111' the {_":1er11:1g:.11i meta-sedimentary
the Cherangani 11tet1'1—see'it':L1.ntar3-' cover ee3'er at at the the kyanite '113-1'1:1:'te grade
grade
iea3'i13g no
leaving 1111 apparent
apparent lower 11133'er grade
grade metasediments
11'1e.1aset.1:1'1'-.1e:1 s t'O 111 ,the
the west, nest. tends tentis to te indieate
indicate that that the the
1'.-111111111 anti
folding pi:1stiL'=.1l‘.3-' Liei'ernting
and plastically deforming 'superincumbent sttpe1'111e11tnhent reeks rocks we're 33'e1'e squeezed
3111'1'11'1i outwards 11.111133":11'tls
te33'111'ds. the
towards the1west' 3L'st in 11‘: nappes,
1t'.1p-".1es.111_133'
now removed 1'e111e3-'1'-.:d by '1_13" the
the same same. deep deep er11st'1111
erosion that that has has revealed
1'e3'e1'Lie d
the sheared
,the sheared:-1nd resistant foundation
and resistant t111111LL1L11111 113'er over which 33'l1i1:|1 they th-e3-' were 33'1L'.re forced.
i'ereed.
Seine confirmation
Some 1:11:11ir1'11atit111 111' of the it"tLLL1111'1tt'a'. nature
the fundamental 1111:111'e and and magnitude
tttagnitntie of ei' shearing
stLLtt1 ng in in the
the
t'enndatien is
foundation is gi3'ert
given by l13' 11LL11rrL1111'3
occurrences ei' peritietite in
of peridotite in the nerth—eentrai part
the north-central part 111'
of the the area:
area;
these
these 11u1e1'eps
outcrops followi'1_11l1:133-' 11a north-westerly
nerth- 33'estL'.-: 13' trend
trend eetttitttted
continued by h3" a11 series et' sitniiar
series of teriti11:ite
similar peridotite
hedies reeerded in
bodies recorded in West331L1st. Stilt
Suk idearle.
(Searle, 1952, 13152, p.
p. iii-1311
18-19). Stteh Such 111 rahasie intrttsiens
ultrabasic intrusions are are
LtitL'tt found
often 1'111111d in
in deep
deep shear shear :1'1'111es
:wnes sit11atet 111111rgi1:t'. '1l3' to,
situated marginally 111 fold
i'ei 1i beLts
heirs of et' alpine
alpine type, t3'1'.e. and
and
are probably
are prehahl3'it1tt'L111etl
intruded ti: tring the
during the initial siaaes of
initial stages et' erege't3'
orogeny t'I-iess. i‘11:1:1. 31.
(Hess, 1955, '1‘-.1111.
p. 393).
1' 1'1} Deposition
(b) D11'pt'1.1.-"11'1'111 and
11.1.1.1." Metamorphism
.-"|.-'i"L'"L'1'1.1.1:1'11'3111'11'1111 of
1131' the
the Cherangant
C'Li'1'1'11113111'111L1' Meta-sedimentary
.-'3-"L"'1't1'.'-_1'1-'.'.1'.1'.111.'1_1'.11:11-3- Rocks
Hayes
The 3111thtrn {'herangani
. The southern Cherangani rocks, although strongly 1'11ei1s.al1.h11111_1i'L strengl3' 111et11111111rph11setl.
metamorphosed, are elearl3'
ue clearly
I'Efl‘li—T'i‘l'lifiliit'lf 1'15
recognizable as a1'1 sequence
SEQUENCE of 311' sandstones,
sLt‘ILIsLLL tes. calcareous
ettiL'aL'e-.1L:'s sartt. litnestnt .es. and
sands, limestones, tttttdstnnes
and mudst'Ones
33'ittt
with rare rare volcanic
3"11]L'ani1: intercalations
ittterettiaiiens which 33'hi-L'h have
have ,beenheen converted
e1‘1113'er‘1eti to 111 the the 11311111“:
appropriate -1.‘11'i:1te Itit‘itfib
meta-
rn1_11'p':1ie rock-types
marphic 1'11elt-t3'pes tieset'ihed
described previously. pre3'ie'Ltsi3'

- 'L'1ssi3e pure
Massive pare metamarphic
"'*111'1L11p.1i1.. quartzites
t3=LtL-t1't;11.ites 1111:1111.
assaciated aied with
33it't1 great
great thicknesses
'1'I_1iei~'.Jt-L'sses .ofcalcareous
11f e'Ltieateetts
par: -et1eiss1:.s 111'
para-gneisses para—granniites and
or para-granulites and aa general
ge11eral"'p:-1t:eit3'
paucity in in the
the seeeessien
succession 11f of antphrhelites
amphibolites
of1" volcanic
3'1'1le anL'e erigin. indieate that
origin, indicate that the the eriginal seti1111ent111'3' sequence
original sedimentary seenent'e was 33-'.'-1_s probably
prehahl3'
depesited in
deposited in the
the sie33'i3'
slowly stilesiLling
subsiding shelf shelt" region
t'egien marginal
111argittal to 1e a11 teotonically
teetenieaii3 mobile 11"1'11"11ii e geo-
gee—
s3't'1eiit1e in
syncline i1'1 33'i
whkh ieh great. 1l1iL"1:L11-L"sses of
great thicknesses 111' g1'e3'33'ae11e
greywacke and and 3'1'ie'L-1nie
volcanic rocks :':11:i~':s were
were deposited.
1i1.=:p::1si‘-Led.
f The distinctian
ti'stinetien betweeni1et33-'1::'.':1.L.orthoquartzite-limestone
11'1."'11.1"=11.L.-1te ii111-L's1'L111-L-1 aet'ttttttt iatietts 1:111 the .one
ante hand, i1 .nd. and and
The accumulatians on the
.e333aLl-LL 3-'11leat'Li1: seer-11131.
greywacke-volcanic accumulations =L1t1'. 1111.11 111'
on1 the the other,
ether. has he e11 drawn
has ,been 1i'1a331'1 by
i13' Kay
K1131 (1951,
{_ififi. p. p. 31711:
86);
the Let'nter are
the former are ge11e1'111i31
generally found i"-11-.11111 in in the heits 111"i1'.‘.L'rt111_'tli:-1Le
the belts of intermediate stahiiit3'stability, er or 111it1L1et1s3-'11L'.1it1es.
miogeosynclines,
situated between
situated het33-'eett the the stable
stahle continental
eentinental margin, margin. and and aa more mere active
aeti3-'e outer
ettter gL11113
geosynclinal11L1111L11
heir in
belt in which
33'hieh valcanic
31eieanie island-arcs
isiand—ares are liable to
are liable 111 fOrIn.
1111111.

..
 28
28

Subsequent to
Subsequent te depesitien
deposition thethe Cherangani
Cherangani rocks reeks were subjected te
were subjected increasing heat
to increasing heat
and directed
and pressure as
directed pressure as the
the probable result of
prebable resU!lt crustal desynss'ard
ef crustal downward 'budding beneath the
buckling 'beneath the
thick sedimentary and
thick sedimentary and yelcanic accumulatiens ef
volcanic accumulations the geesyncline.
of the geosyncline. In the deepest
In the pertiens
deepest portions
the desynbuekle
of the
ef down buckle both beth geesynclinal
geosynclina'l floortleer and
and its its eyerlying sediments were
overlying sediments were recrystallized
recrystatlized
and migmatized and
Ulltimately migmatized
and ultimately re-fused se
and re-fused that the
so that the eriginal identities ef
original identities the different
of the different
reeks were
rocks practically ebliterated.
were practically obliterated. The The zonezene ef of maximum intensity fer
maximum intensity this precess
for this process is is
eften
often reughly
roughily ceincident
coincident withwith the.
the axis
axis efof maaimum
maximum eriginaloriginail sedimentatien,
sedimentation, hut but net not
ins'ariably se.
invaria:bly so, as geephysieal data
as geophysica'l tends te
data tends show that
to shess' some aetis'e
that seme. downbuckles ef
active dess'nbuckles of thethe
present day
present asymmetric l'hleinesa.
are asymmetric
day are (Meinesz, 1954, 11354. p. 1955, p.
152, 1955-
p. 152- p. 32?. Bucher, 195?:
327, Bueher. p. 260—
1957, p- 260-
Edd)-
266).
The sediments and
quartzose sediments
cearser quartaese
The coarser sandstones apart
and sandstenes apart frem recrystallizatien and
from recrystallization and
the growth ef
the gresyth bietite, remain
of Ibiotite, comparatively unchanged
remain cemparatiyeiy unchanged es er aa wide
over range at
wide range of applied
applied
pressure and
pressure and temperature,
temperature, but but the mudstones and
the mudstenes and calcareeus sediments are
cailcareous sediments mere sensi-
are more sensi-
tis'e. so
tive, certain distinctive
that certain
se that minerals. stable
distinctis'e minerals, stable at at the peak of
the peak metamerphism. are
ef metamorphism, are
preseryed in
preserved in them. and ferm
them, and form the basis ef
the 'basis the facies
of the olassification er
facies classificatien metamerphie reeks
of metamorphic rocks
(Eskela. 1920,
(Eskola, 1920. pp. Turner, 1948,
143-194. Turner,
pp. 143-194, 1948. pp. pp. 61-107, Turner and
61-107, Turner and 1-"erheegen.
Verhoogen, 1951, l'rlil.
pp. 433-430. Fyfe,
pp. 433-480, Turner and
Fyt'e. Turner and li.-"'erbeegen.
Verhoogen, 1958, Wit-239}
pp- 199-239).
liilfii. pp.
Altheugh sillimanite
Although identified in
been identified
has been
sillitnanite has small ameunts
in small amounts in seme ef
in some of the reeks.
the rocks,
the assemblage of
mineral assemblage
characteristic mineral
the characteristic ef the
the pelitic schists ef
pelitic schists the seuthern
of the {'herangani
southern Cherangani
hills is kyanite-almandine-bietite-eligeclase
hiFls is kyanite-almandine~biotite-oligoclase se that these
so that rocks are
these reeks are placed the kyanite-
in the
placed in kyanite-
musces-‘itc-euarta subt'acies
muscovite-quartz recognized by
subfacies reeegnizcd Francis ("l“).‘iti.
by Francis (1956, p. and Fyfe.
356) and
p. 3:36) Turner and
Fyfe, Turtter and
Verhoogen {19:38. p.
‘t-"erheegen (1958, 228). This
p. 22-8“). mineral assemblage
This mineral assemblage is common'ly deseleped
is eemmenly developed in pelitie
in pelitic
sediments under conditions
sediments under cenditiens of ef temperature
temperature and pressure intermediate
and pressure intermediate !between
betueen thesethose
ferming tbc
forming the staurelitc-euarta
staurolite-quartz and and sillimanite-almandine
sillimanite-almandine zones aenes in regitms ef
in regions of prtigressise
progressive
regienal metamt'irphism.
regional metamorphism.
The calcareeus
The calcareous rocks interstratified and
reeks interstratihed iset'aeiai ssitb
and isofacia!l with these pelitic kyanite-bearing
these pelitic kyanite-bearing
schists are
sebists are typically composed et
typically eempesed of hernblcnde-diepside-cpidete.
homblende-diopside-epidote, or aln'utndine-diepside-
er almandine-diopside-
hornblende assemblages-
hernblende together ss'ith
assemblages, tegether oligoolase-andesine, scapelite.
with eligeeiase-andesine. bietitc and-"er
scapolite, biotite and/ or
quartet. and
quartz, and hence fail inte
hence fall the almandine-diepsidc-bernblcnde
into the almandine-diopside-homblende subfacies. Beth
subfacies. the pelitie
Both the peilitic
kyanite-bearing assemblage, and
kyanite—bearing assemblage. calcareous almandine-diepside-hern'elende
the calcarceus
and the a:lmandine-diopside-homblende assem-
assem-
blage. eenstitute
blage, subfacies ef
constitute subfaeics of the almandine amphibelite
larger almandine
the larger embracing the
facies embracing
amphibolite facies the
preducts of
products medium— and
et' medium- high-grade regional
and high-grade netamerphism.
reghsnal metamorphism.
it is
It is et‘
of interest
interest that
that the Cherangani rocks
the Cherangani reeks are
are ef
of aa less
lowerer metamerphie
metamorphic grade. grade than
than
these seen
those seen totn the
the seuth-east
south-east inin the Kitui area.
the Kitui area, it here sillimanite
where si~limanite is is the
the typical
typical grade-indes
grade-index
et" the
of peiitie schists.
the pelitic schists, and
and is
is isetaeial
isofacial ss'ith calc-silicate granulites
with calc-srlicate granulites et' of Eskela's pyresenc-
Eskola's pyroxene-
hernfels
hornfels facies {Sanders l‘eliisl
facies (Sanders, 1954 A.A, p.p. 35).
35). The
The higher metamerpbic grade
higher metamorphic grade in Kitui is
in Kitui is due
due
te the
to the presence
presence immediately
immediately tn the nest
to the west et' large areas
of 'large areas ef migmatite and
of migmatite and granitic
granitic gneiss
gneiss
ts'here recognizable
where reeegniaable metasediments
metasediments have been eblierated
have ,been oblierated by by progressive
pregressis'e granitiaatien
granitization in in
the now
the new deeply-eroded
deeply—ereded asial pertinn of
axial portion et aa fold
teld belt
belt tea.
(op. er'r..
dt., p.p. .ifil.
35). Inln centrast.
contrast, the the
Cherangani rocks
Cherangani reeks have
haye suffered
sufi'ered eutly
only ss'eak
weak granitiaatien
granitization es'ideneed
evidenced by by thethe gress'th
growth ef of
albite-eligeclase
albite-oligoclase perphyreblasts
porphyroblasts in
in the
the sediments. Petash metasematis
sediments. Potash metasomatism, fir-pnr-lit
lit-par-lit
injectien, and
injection, and ether
other signs
signs etof ads'anced
advanced granitiaatien
granitization are are net
not seen-
seen, and cs'idently the
and evidentily the
reeks haye
rocks have escaped
escaped thethe highest grade ef
highest grade of metamerphism
metamorphism attended attended Iby by granitiaatien.
granitization, due due
te their
to their marginal
marginal position.
pesitien. During medium-grade metanuirphism.
During medium-grade metamorphism, besses'er.
however, the recrystal—
the recrystal-
lizing rocks
lizing reel-ts were.
were under
under sufficient.
sufficient directed pressure and
directed pressure and applied
applied temperature
temperature te felt] and
to fold and
buckle.
buclde, and and inin their
their mere
more rigid parts te
rigid parts to shear
shear eutu'ards
outwards and and assay
away itemfrom thethe asial regien
axial region
ef
of the geesyneiine. as
the geosyncline, as is
is shess'n
shown Iby by eenstant
constant es'ertarn
overturn ef of feids
folds ten-ards
towards the nest (Piates
the west (plates
VI and
VI and Kill} with ubiquitous
VII) with ubiauiteus shallow
shalless' eastward-dipping
eastward-dipping cleavage
cleas'age planes.
planes.

2.
2. Intrusis'es
Intrusives
(a) Ft’t't'i'ftlfifi
[it'll Peridotites i“ e's'

A s'et'y
A very ceat'sc.
coarse, dark.
dark grace peridetitc Occurs
green peridotite occurs in in scattered
scattered eutereps
outcrops en
on the
the nerthern
northern
side
side ef
of the
the Ts'aeia
Nzoia valley in the
vaUey in regien, et
the region of Tesetti‘s
Tosetti's Dritt Drift. The
The eentacts
contacts etf indis'idual
of individua'l

-
.-
1

29
29

intrusions ebscured by
are obscured
intrusiens are seil cover,
by soil an indistinct
but an
ceser. but ilessi-laminatien seen
indistinct flow-lamination in seme
seen in some
espesures suggest that
woU!ld suggest
exposures t‘i’fltlid are the
they are
that they the parts of sill-like
parts ef sill-like 'lenticullar bodies dipping
lenticular hedies dipping
rewards the
towards Boulders ef
nerth-east. Beulders
the north-east. of peridotite nerth-west te
follow aa north-west
peridetite. fellew to seuth-east trend
south-east trend
distance ef
for aa distattce
fer abeut eigltt
of aJbout miles. reughly
eight mi~es, parallel te
roughly parallel the axis
to the of the
axis ef Nzoia valley
the Naeia vaHey
hetw-‘een Tosetti's Drift
between Tesetti‘s and Kaisagat.
Drift and Kaisagat.
Under the mierescepe
Lindcr the olivine and
microscope elis'ine and deris'ed serpentine are
derived serpentine seen te
are seen constitute mere
to censtitute more
than tine-half
than ef the
one-ha'lf of reek. with
the rock, lit-"persthene and
with hypersthene and atigite making up
augite making the remainder.
tip the. remainder. TheThe
I ertherhembic pyresene eceurs
orthorhombic pyroxene occurs in in large. zened. stihhedral
large, zoned, subhedral phenocrysts sometimes with
phenecrs'sts semetimes with
T
purple and eften
margins and
pleeehreic margins
purple pleochroic intergrewn with
often intergrown with replacive 'erewn atigite.
replacis'e brown augite. AA serpen-
serpen-
tinetts mesh
tinous released iron
much released
eentaining much
mesh containing ere. accempanied
iren ore accompanied by amounts ef
smatler ameunts
by smaller of
red-brew-‘n plcechreic
red-'brown iddingsite. dis'ides
pleochroic iddingsite, divides thethe elis'ine inte numerous
olivine into unaltered and
numereus unaltered and cerreded
corroded
some ef
patches. seme
patches, which are
of which are surreunded
surrounded by narrow kelt'phitic
last narrew kelyphitic rims of antigerite.
rims ef Feikilitie
antigorite. Poikilitic
crystals ef
crs'stals also eccur
olivine alse
of elis'ine occur in in the pt'reseites. as
the pyroxenes, as iii specimen 34
in specimen 34/609 from ene
fife} frem mile
one mile
seuth
south ef Kekerewa. and
of Kokorowa, and 34."ti-—ltl
34/640 frem from three miles \K'HW.
three miles WNW. ef of Tesetti‘s
Toseui's Drift.
Drift.
Further eutcreps ef
scattered outcrops
small scattered
Further smaH peridetite eceur
of ,peridotite occur near tlte western
near the margin ef
western margin of the
the
area
area seme
some tw'e
two te
to three.
three miles
miles nerth
north ef
of the
the l‘s'iteia.
Nzoia river.
river, near
near thethe Hemsteadls
Hemstead's Bridge-
Bridge-
Laigiri road.
Laigiri The}: are
read. They similar in
are similar eempesitien to
in composition tn the
the peridotite t"ar Tesetti's
peridetite near Tosetti's Drift hut
Drift but
in specimen 3t
in specimen 34/658 the elis-‘ine
6238 the. olivine is mere scrpentinized
is more and augite
serpentinized and is net
augite is so ahttndant.
not se abundant.
occurs in
Hypersthene eecurs
Hs'persthene sub-idiomorphic tinned
in suh-idiemerphic zoned prisms with celettred
prisms with pleuchreic margins.
coloured pleochroic margins.

it i) D
t:(b) rife ri a--- t
Dolerites
Dolerite ds'kes
Delerite intrusive into
dykes intrusive inte the. migmatites and
Turbo migmatites
the Turlee were recerded
granodiorites were
and grttnedierites recorded
from aa few
frem leealities. hut
few localities, but none were feund
nene were in the
found iii southern Cherangani
the seuthern Cherangani mIls. The ds'kes
hills. The dykes
generatly range
generally between 11 feet
range between and 2t]
foot and feet irt
20 feet. width and
in width their etitcreps
and their are eften
outcrops are indi-
often indi-
cated
cated byby dark
dark iren—stained
iron-stained sphei'eidal
spheroidal hatilders
boulders with
with aa weathered
weathered skin
skin beneath
beneath which
which the
the
fresh dolerite is
fresh delerite exceptionatly. hard. In
is eseeptienallsi-hard. In general appearance and
genera'l appearance and range of cempesitien
range ef composition
these
these d's'ke reeks are
dyke rocks are similar
similar to in these
those descrihed
described fremfrom the Brederick Falls
the Broderick Falls area
area te
to tlte
the
west
west (Eileen. 1954. p.
(Gibson, 1954, p. fill}.
32), and the Kakamega
and the Kakamega area in the
area to the seuth-west
south-west illuddlesten.
(Huddleston, ltlfsl.
1954,
p. 19),
p. of the
19"}. ef present area.
the present area.
in thin sectiett
In tltitt texture and
the testure
section the composition indicates
and cempesitien that the
indicates that rocks has'e
the reeks heen
have been
subjected te
subjected to same degree ef
some degree metamorphism. "they
of metamerphism. They areare usually with an
holocrystalline, with
usually helecrs'stalline. an
ophitic er
ephitic or intersertal texture. 'l'he
intersertaJl testure. ranges frem
felspar ranges
The felspar andesine te
from andesine to lahraderite
labradorite buthut isis
ctiintmanly
common~y aa saussuritiaed hasic andesine
saussuritized ,basic andesine with
with peerls'
poorly defined
defined twinning.
twinning. 'l'he
The ps'resene
pyroxene is is
aa pale
pale green
green dust}? pigetinitic augite'.
dusty pigeonitic augite, aceempanied
accompanied by hs' acccss‘ers'
accessory iren
iron tire
ore and
and hietite.
biotite.
.alteratien et."
Alteration plagieelase ht-
of plagioolase by micrt'tgraphic
micrographic grt'iwth
growth ef of fresh
fresh fetspar
felspar and
and quarts:
quartz partis'
partly
ehliterates
obliterates the
the eriginal
original laths.
laths, anti
and the
the margins
margins ef p}--‘re.sene against
of pyroxene against feispar
felspar are
are in
in cense-
conse-
quence
quence eften
often irermicular.
vermicular. Partial
'Partial alteratien
aJlteration ef
of pyresene
pyroxene te to hern'elende.
hornblende, particularly
particu~arly atat
the
the margins.
margins, is
is cemn'ien
common asas in
in specimens
specimens 3.4 T—ltl anti
34/740 and Ll 7'41 frem
34/741 from the
the Hipkarren
Kipkarren riser
river
setert
seven tt'tiles
miles Still-i.
SSE. tlil
of 'l'urhtt
Turbo. Specirt'ten
Specimen 345731}
34/730 frem
from Rethntan's
Rothman's farmfarm shes-sis
shows aa mere
more
advanced
advanced stage
stage ef
of alteratien
alteration in
in which
which idiemerphic
idiomorphic er
or granular
granular garnet
garnet eccupies
occupies cerertas
coronas
between
between the plagitiiclasc and
the plagioclase ps'resene and
and pyroxene and is
is accempanied
accompanied ht''by sermicules
vermicules et'
of etiarta
quartz
liberated
lirberated during
during the
the fermatien
formation efof garnet.
garnet. Bietite
Biotite is
is distrihuted
distributed iii
in flakes
flakes threugheut
throughout the
the
reek.
rock, and
and iren
iron are is eenccntrated
ore is concentrated in lccal skeletal
in 'local patches. and
skeletal patches, and aise
also eecurs
occurs in
in dusts-
dusty
granules
granules in the ps'rnsenc.
in the pyroxene.
3.
3. Tertiary
Tertiary Lat-as
Lavas and
and 'I'ufl's
Tuffs
listensis'e
Extensive sheets
sheets tit~ phenttiitic lava
of phonolitic ltis'a underiie
underlie the the hash": Uasin (ills-hit plateau nerth
Gishu plateau north Ll":
of
filderet. ct‘ts-ering
Bldoret, covering apprrtsimately
approximately tine-half
one-half elf of the.
the entire
entire area area and reaching aa maximum
and reaching maximum
':' thickness
thickness in in the
the extreme.
extreme east.
east. The
The highest parts ef
highest parts of the the plateau plateau stand
stand atat an
an elet'atien
elevation ef of
ahettt
about Salt-JD
8,000 feet
feet near Hanterin. while
near Kamorin, in'tmediatels' east
while immediately east ratof the
the area.
area the lease cf
the :base of the
the
pheneiite can
phonolite be seen
can ,be in tlte
seen in the face
face efof the l-ilges'e escarpment
the Blgeyo escarpment near near Tamhaeh
Tambach at at anan elesa-
eleva-
tiett
tion efof aheut
about area
6,200 feet
feet fShacsleten.
(Shackleton, ltlfl.
1951, p. p. 373).
373), se so the the tetal
totaJl thickness
thickness ef phenelite
of phonolite
at
at the
the eastern
eastern margin
margin ef of the
the area is ef
area is of the
the erder
order et' l.t:it'_'it'_'.t feet.
of 1,800 feet. I
\,

L
..
30
St]

The northern
, 'The northern and and western limits .of
western limits of the
the tlews
flows eemprising
comprising part part of the Vasin
of the L'asin Iffi'rishu
Gishu
yoleanie aeeumnlatiens are
vo<lcank.accumuiations marked by esearpments whieh ean ,be
are maikedlbyescarpments'whichcan be traeed
traced in in aa northerly
northerly
direetion from
direction' from near
near Karena
Karuna alonga!long thethe western
western sideside ofof the
the Moiben
Meiben yalley
valley to to Kaisagat.
Kai,sagat,
where isolated
where isolated outliers
outliers of phonotite cap
of phonolite eap aa series
series of of small.
small, flat-topped
flat-topped hills oyerleoking
hN>lsoverlooking
the
the Z‘s'aoia riyer. From
Nzoia river. From here.here the
the esearpment
escarpment eentinues
continues in in aa north-westerly
north-westertIy direetion
direction
towards Tosetti's
towards Tosetti's Drift;
Drift; it it makes
makes aa bold feature flanking
bold feature flanking the the southern
southern sideside of the Nzoia
of the Nzoia
yelley
vaNey anti
and extends
extends through
through EiwaZiwa to to Matunda
Matunda hill. hi~l, near
near Heey’s
Hoey's Bridge.
Bridge. South
South ofof 'Hoey‘s
Hoey's
Bridge the
Bridge the margir
margin of the 'lava
of the laya isis embayed
embayed by by the
the va~ley
s-altey of the Little
of the Fania. and
Little Nzoia, and then
then
takes an
takes an areuate
arcuate sweep
sweep to the south
to the south of of Soy-'sambu-
Soysambu. 'l'he Edges of
The edges of the
the plateau
plateau are are again
again
seen
seen at.
at 'l'urho.
Turbo, wherewhere the railway follows
the raHway foHows the the font
foot of of the
the phonolite
phonolite esearpntent.
escarpment. Between
Between
Soy and
Soy and Tur'oe
Turbo the the Sergeit riyer has
Sergoit river has deeply
deeply ineised
incised thethe phenolite whose boundary
phonolite whose boundary eon-con-
tinues
tinues southwards
southwards and and extends
extends to to the
the region
region of of Selby
Sel}by Falls.
Falls, where
where the Sesiani river
the Sosiani riyer
plunges
plunges front
from thethe edge
edge of of the
the plateau
plateau sentesome six
six rnilEs
miles to to the
the west.
west ofef Eldoret
Eldoret [Pltte
(plate Ii tell.
(a».
Phonolite
Phonolite at at the
the summit
summit of of the
the esearpments
escarpments eyerlooking
overlooking the Heeia and
the Nzoia and Sesiani
Sosiani
yalleys is
vaJlleys is atiot'it
about 200lit-{l feet
feet in
in thiekness?
thickness, somesome 1,600
ltit'tt'l feet
feet 'less
less than
than that
that at
at 't'anihaeh
Tambach 25 miles
25 miles
to the
to the east-
east. 'l'his
This marl-ted westerly thinning
marked westertIy thinning, eeupled
coupled with with the
the itow-orientatit'in
flow-orientation of pheno-
of pheno-
erysts
crysts in the lavas,
in the laxas indicates
indieates that they entered
that they entered the the. Vasin
Llasin Gishu
Ciishu from
from thethe east
east and
anti south
south-
east and
east and werewere probabily
probably extruded
extruded in in anan area nt'iw oeeupied
area now occupied by by the
the Kamasian
Kamasian seetion
section of
of
the Rift
the Rift Valley.
Valley. |tiltnly
Only aa single
single flow
flow isis present
present at at the
the north-western limits of the
horth-western <limitsof plateau.
the pilateau,
but it
but is likely
it is likely that
that seyeral
several separate flows contribute
separate flows etiintribute to to the
the greater thiekhess of
greater thickness of phonoilite
phonelite
seen
seen inin the
the nye
Elgeyo esearpment.
escarpment.
The earliest lava
The ear<liest tax-a flood
hood spread
spread aeress
across aa surfaee
surface of gentle relief;
of gentle relief; the tongues of
the tongues of
toying lava
moving laya probably
probably followed
followed va~leys
ya'lleys and
and filled
filled depressions
depressions before
before covering
eewering the
the higher
higher
interfluyes which
interfluves whieh perhapsperhaps werewere notnot ens-'eloped
enveloped until until the
the arriyal
arrival of of aa subsequent
subsequent flow,
tlew.
so the
so the totall
total thickness
thiekness is is 'liaij)le
liable toto vary
sary with
with thethe locality.
loeality. Some
Some estimate
estimate. of of the
the. amount
amount.
of variation
of yariation can ean be be made
made fromfrom thethe. surface
surfaee geology,
geology. thus thus toto the
the north-west
north-west of of aa iline
line
drawn between
drawn between Soy Soy and Iyloihen the
and Moiben the depth
depth from
from surface
surfaee. toto the
the base
base of the. phonolite
of the phonolite
is bets-seen
is between 150 Ilfiti feet
feet and
and Ext—it} feet; Eldoret
300 feet; L-"lderet township
township stands stands on on approximately
approximately shift 400 feet
feet ofof
phenolite: whiIst
phonolite; whilst 'between
between Eldoret
BIdoret and and Sergoit
Sergeit the the thiekness
thickness of of lava
laya can ean bebe expected
expeeted to to
range up
range up toto 600titltl feet,
feet, increasing
inereasing to to over
oyer 1,000
Ltit'lt] feet
feet inin the
the Kamorin-Kachouwat
hiamtwin—Kaehouwat region. region.
These estimates
These estimates are are subjeet
subject to to modification
n'teditieation when when appilied
applied to to the layas in
the ,lavas in proximity
proximity to to
Basement System
Basement System inliers whieh appear
inliers which appear at at. Nel's
Hel‘s Bridge
Bridge {Plate
(Plate l1 (b))
thrill and Sergeit (Plate
and Sergoit tPlate
ll [at].
II (a)). The hfel's Bridge
The Nel's Bridge inlier has resulted
inlier has resulted from
from the the erosion
erosion andand removal
remoyal of phenolite
of phonolite
eoyering an
covering an origina'l
original elevation
eleyation of of Easement
Basement System System rocks,
reeks. unUke
unlike Sergoit
Sergeit Rock
Roek which,
whieh.
judging
judging by by its
its present
present height
height of of titltl
600 feet aboye the
feet a'bove the surrounding
surrounding lax-a.lava, would
would appear
appear not not
to have
to haye been
been covered
eos—ered by by even
es en the
the highest
highest. phonoUte
phonolite flood.flood.
is
A narrow
narrow strip
strip of
of Easement.
Basement System
System reeks
rocks aimest
ailmost surrounded by phenolite
surrounded by phonolite in
in the
the
Karena region owes
Karuna region its presenee
owes its to faulting
presence to faulting and
and subsequent
subsequent erosion.
erosion.
The sueeession of
The succession layas and
of ,lavas is:
tufts is:-
and tuffs
[3] Vpper
(3) Lfasin Gishu
Upper Vasin Phonolite.
Gishu PhonoUte.
[2) Lower
(2) Uasin Gishu
Lower Vasin Phenolite.
Gishui Phonolite.
ti} Miocene
(1) h-tioeene Tuffs
Tutfs and Grits (Moiben
and Grits [Meiben Beds and Selby
Beds and Falls Beds).
Selby Fal'ls Beds}.

tit htier'ese
(1) Tires AND
MIOCENETUFFS xxo {jarrs
GRITS
Some
Some Still feet of
500 feet of stratified
stratified tolls
tuffs and
and grits
grits are
are toto be seen beneath
be seen phonolite at
beneath phonolite at
Tamhaeh. just
Tambach, outside the
just outside the eastern margin of
eastern margin the area.
of the They rest
area. They rest unconformably
uneonfermably en on
Basement System
Basement System gneisses
gneisses exposed
exposed in in the
the middle
middle and lower parts
and lower parts of the Elgeyo
of the esetti'p—
Elgeyo escarp-
meet. and
ment, and theirtheir Miocene
h-‘lioeene ageage isis indicated
indie:-tted "eeth
both byby eontained
contained nephelinite pebbles deris-ed
nephelinite pebbles derived
from early .‘stioeene eruptions and y their ['essil fauna. whieh ineludes' eroeodile. tors
from early Miocene eruptions and by their fossil fauna, which includes crocodile, tor-
teise and
toise possibly a
and possibly rhinoeerid {Shaekleton
a rhinocerid (Shackleton, Writ.
1951, p.p. ETSJ.
373). "Joleanie
Volcanic ashes
ashes and
and inter—
inter-
stratii'ied
stratified gritty
gritty er
or tutfaeeous
tuffaceous sediments
sediments were
were deposited
deposited during
during early
early Iylio‘ene
Miocene yoleanie
volcanic
 .__1.—_-_I _ -.— ——. ._.._.-_ _

'11
3i
n.

1:11.1111111111 '.11'..t'
eruptions were :11'1er.I.-'
and I.I.'.:"e afterwards -1.1.1I1 LI.I
covered .II:':'LI.". by the 1"11'
'11. the first 11 floods 1"..1.".I.1.I. .11' I.I'11.I11.'I1.I.1 lava, so it is
of phonolitic
Ii '1.
1.1.-
1'.-1 .-.
l.‘.:ui."'1.=
--
:""-.-" -I-.-
-
L“

likely that
likely that 11Er11ii:11‘
similar bed... beds 111 to th.:.~1e
those LI'exposed .II'.11t.'.I.I.I.eI.i I.1t
at '1'1-‘11‘1‘1b1'tet‘.
Tambach .‘1I'e are I.1-'i1ier1pi'e':1e'1
widespread beneath 1:.1: 11I .1111 111:
the 1.3.1.1i1'1
Uasin
Gishu phenelite and
131111111111 phonolite
{'.I-1.11.1 ~plateau 111'.Ih'.'1t:-‘13.' .I.-.:eI-111.
.1111! probably occupy former t'.1r11'I. LI1' 11.111 depressions on tthe
.:...11 .Ir1.I1 .111 h: :ILLEI—TI-Iteeette
sub-Miocene
I HUTLElCL". They
'surface. hI"-”1'IC"-"1'."". I'L'i'i'IJEL
Ell—'.'.“ however,
ThC'II' are, only seen f‘iC-L'i'i at .1'? a1.] few I'Tlt'iI
i131“. points 'I.:I. 11.1113
at the edges _ 135 of
$1.11- 1'-'It' I'.
. Il-

the 111.111.1111 11111;.-

.1e plateau and
are much thin-111:1
clearly tttttL'tt
'_11‘e eEeI.t'tiI.‘ thinner than then the the Tambach '1'11t'ith.t1:h eeeLte. sequence. I.”.t‘1 'e. They The}? 1'11“: are 10t exposed in
best" .:.I1p1111e1it in 1111.1
tWo
"""'."" ‘.'11.:1'i1':'1
areas, along the
the first :1'.'I..'.I.:1g the edges of the
.j'II_I.:I_'. 1.1:” the _11_'Ii.'1_I11—..1IIII.'I.1
Moiben-Tosetti's Drift escarpment, ..Ihd
i.I'i'1t e11L':-'11'I.11“-1I:I.1t. and the thewween
secondI. Li
in the:.“'I.'..I.I'.iI_111i
Sosiani valley Selby 1";1111.
near Seth-'.'
:.'.'.'.-.'Ij. :1I':.I.I' Falls.

r: '-Ir
(a) The Moiben Beds
.LL.

€115.11.11111'e11111e1'111e grit-I.
>'Brown-weathering grits '.111L'tand blue-grey' tuffsI. LItttL'a‘..:1:1
hiI.1eIgi'eI.-I t.1_tt"11' outcrop some 111111.: t'.I.'.'1
two miles north.east .11'
milee 11.'I1':‘1‘.—L:11.I.-‘. of
“11.111.11.11 post
Moiben, office ..I-1'
1.111111 L'Ii'iiee 3.1111'1131 _I':1"111
on. Muringa farm 1P11I: No. 1‘.-15.13.71.
(Plot ?‘I..'I. 6837), where about I'.-'.I
11'11LI1'LI :.1'.1.I-.:‘. 20 '.'ee1 of .11.I.I:'II.
feet LIt' poorly
sediments t'.'I:'r:I.
exposed eetii111en‘...
21.11.111.21 form :1.a t;1i'.I. thin -:.':1111:'I.1I_-I
capping two 111.1 111'or three acres i11
11':1.I.: '.1.'1'e1'. extent .1‘.
in exteh at the crest .11'
the L'TLIrIIt of a
1:111?
spur ..1‘1'e1'lL'111I1111‘1g
overlooking the 3.1.11.1 valley.
the. Nzoia I.'.1Jl.I_'I_.. 'i'he 11.111.11 beds
The basal bed. .11”: are t."".‘r'.'t‘.
coarse .I1.':. felspathic
....I.1:I...t‘lt.. 121212111:1.1111e1'.tt.:11.
conglomerates,
I.I.'e:.‘.'=."..:ri'.1e 111'
weathering of Iwhich
.-':'I .' .1.":1 has11;.I1 released
1'e1L..'.1IIeI:! numerous
11.1 tier-.11... well-rounded
.I.'I.'etl—.I'..'II-1i1.1e.1 L'_;I.1.11':z
quartz. pebbles IIh‘I1LI. 11:11:13
having 'a.I.
L5111iI-teti1'e. yellow
distinctive '.LIH..II.I-' 1'I1' :11'.I'-.I.'11 external
or brown staining. The
1::11L'I1'h.ti .I.”~t..f'.‘.ii'.~§. conglomerates '.I-:e.II.LI'ti:.1iiI.
The L._".I11-:-Ii..Ir11-.I:";'.I-._I.I. are overlain by hf. grim.grits.
It] thin
In section tepeeit
t.I.iit eeetiLItt (specimen ‘1‘1LIt1 34 34/580), .I'.-htflIt- the matrix of
the matrix .Ii' thethe 1:011:41.
conglomerate and the
:11'111.-I".'I.t.: 1111.1 the 1'11‘it
grit isi.I'.' I'.eL'1‘.
seen
t1'1 .'.'111:1i.I1t.
to consist CI'I' of 1-‘11‘11-It1111t‘
angular .i1r11'11'teLt ill-sorted 1:11.111“. grains .11: of L;I.1.'tt‘t.I"-
quartz £11111 alid 1'.-.I1I1p."11
felspar itt in -.‘1p..‘1.‘..t‘t...1.
approximately CLILL'EL'. equal
proportions, LiIIII.-. 11:11 in
;::'.'I;1.I.-1I1i.111.1. eJ11bedded 111 an '.'111 opaline .:e:11e11t.."'111'.:11'.
1:1;1:..!111e cement. grains .11"
Small 131.1111... .I1L'11'11trII-e11I-ie are
of hornblende 21:.1tte.:.:'."..
:1re scattered
:h1'LILJgitL‘ItEt
throughout the. the 1111111171.
matrix, .1'i11'1 with 11I.'L'I:I1:I..'.I1'I-.'
accessory '.'11‘1‘1111111'...
amounts ..It' of garnet.
gamet, it'm'l iron 111'e- ore, 111'1'LItI1e11e.
pyroxene, e11i11111e.
epidote,
hintite
biotite 1111.1
and unite.
rutile. .

Light—eeéeuree blue-grey
Llght-coloured Hue—grey unstratified 11:11.1111111'1e1'1 1.1111 tuffs 11.1111 above t'11LI
occur I..'I.1.'.I.I..: the 1:111:11 grits. In 1111.21211111211
basal 1:11.1111 specimen
3—1 311']. angular
34/381, angular L'i.1:1ti1'.‘clastic 1:.111111itt1ent1'. 11:1:
constituents are 111:1:11 to
seen :ILI quartz,
t.‘.I be 1LI1I1t11r an9
.:jtt:'11"..I'.. felspar iiiw1r11111ei113e. in
111111 hornblende, i1‘1
1 -
' H "II" '.' 'I"1 "'-I "I' '.'J. :11. : |'-' '1. r‘i'I 1 ' -.-. -' "I-I r '-
t_..".'t '9']. :I'1 CIT
fragTI1ents ‘.I.I".' 1-11...’ size
of smaller '.ftLLT'l those
.‘.I1'..I'-:_. than .I.ILIt..1"'1 in
I.1:L‘I.II.. seen 31.91.- A
. .L grits.
1T1 the ‘iL.i.‘.I-11111.1.‘ILL]-‘I
.I:‘\ sub-microscopic .1‘-«..I.
ashy ..I.-.'..:I.
matrix
.:.:-1'..11'.tI_1'.:.I.111.11.:
constitutes more 1111.11 than 1':I.i':I'.'—t1'.tit'1'.'1."t1‘.e
one-half of' the rock. 1'1.‘11:'1..

Similar tuffaceous grit...

Similar 1111'1'11-e-LI-1IL... some ..I:.'I1:‘.'_'1ii'I.i1'1f.f.
grits, I1.I:1'.-e containing fossil [.II-1.111 wood, were I1.-11:11
..'I..I.1.i. .I.-'et'e seen '.'1: at thethe base i.1'_LI.I'-'-.I LIE' thet.“
of 1:":
_.1'1'1.I.1I...1|.1'1e .11
phonolite at 11.11.1111]
several points 11L1I'I12I'. 1.1.1113:I
along :1"... the LI1LI:1IIL1111.'11:
escarpment .I...." overlooking 1131;111:1111. ‘.'the .II..I.I Nzoia
‘I..I.1.Ii:'. '.':1'51LI'1'.
valley. In [11 11' 1'.
all
L':=.'~'.e.I'..
cases, however, '11.1I.I.'LI.1-er. talus
t:1!t1:I.'. 11.1.1.1
shed from t'1'1'1111 the
the e133:
edge .11" of the t'11LI'.".'1-'I..'I.
lava 1.1111111 tends 11.1 to 1111
obscure.I1LII.1:-'..t:1.:
the reht‘: relatiyely 11-211 1111:".soft
undermine :Btfditi'lt‘t'tlfi.
underlying sediments, which can 1112:.
11111.11 I'.".'.11 only be 5311111.. in
'.‘-e found I.1:11ttei'e1'1 blocks
111 scattered beneath the
h..I..'i-1.I1 beneath the phono- ph111111-
1...?
lite eL‘It‘itL'tL't.
contact. A .I'I. brown
'tTIi'1:I.I.'1‘1 tL'..'1".1L'e..'11.1.I'-.
tuffaceous g-Ii'it grit HDL‘L‘J't't'tL‘I't
specimen 3'4 34/595, _“'I'I'I_"I. ‘.I.".1:I'
was1 L'1'111ee2e1ti
collected from t'I.'.'.'It‘1‘1 the the 115.111.“.
slopes
.1'
of the 1h: e11e111'11111e11t
escarpment 11' L11':t1='. four
about 111.11 111ileI1 SSE. ..11'
miles SSE. of T1111:
Tosetti's tti' .I1 Drift,
Dlit't. 1111.1 and :1a .111111111'111ee1111e1'.
similar specimen
11:51.1; comes
34/592, :"1'.Ih1 the
e1111'tLI.I1 from the escarpment 1111.: mile
.:....I1'111IIIII11I one :11'Ii'th—I.I.'eI1t of
111iie north-west .It the .-'I.."L1':.‘I.I'I.‘.Itit.:'h—MLIi'1‘.I':1I.
the Arobobutch-Moiben
. .:....1.I-LL.
confluence.
L.."."i!1.li...£I

I.I'r'.
(b) The '1"f.'.I-I .‘S'.-I.I"."I_1' Falls
Selby ELI...
I-'.-.'.I'.I'. Beds
91.1. Hit ten
About Men feetLee. of ..IIII1111‘1IL1 .1111: and
111.2211 agglomeratic
111' green 1111.1 grey stratified tuff
I_.I_I1'LL._-' .stratified I.I.'e:'e ineeted
t.1_1t't' were beneath
located beneath
The bee-:11
~he basal phonolites phenelitee in itt the S.”1Si'.111i valley,
t1t1te Sosiani .1pp1‘L-I-‘Ititt‘111tel11' one
13.11:}. approximately tttile SSW.
.1111: mile SSW". of of Seth}: Falls.
Selby Falls.
The pyroclastic
The 11.. '.'1'.1-.:‘.11.I115-.: beds
he... Lteeeatted
deposited 111 in 11111
this 'area
.'-".1'e'.-1 I.".1'e
are 111:1.I-11'coarser 2I1er then
than thesethose 1.1.11 seen 'at
.11 Meihen
Moiben;
the I.1LI'1_I._I].1r111-.I.r1.1e
the agglomerate {'111eeir11e11 (specimen 3.1. 34 i Hit.
711), e.1:1t.-1i11:1
contains 1111111e1'.11.1.I1
numerous dark dark nephetihite 1'111ez1..I11‘..I1
nephelinite fragments
1111:1121.1It‘.t‘.g tip
measuring to 'an
up tL'I E. 1:11 11121111111.
.'111 inch enclosed in
across, LI11L'i.11'I.eI.i an 11.111
in .111 ash matrix twee-her with
111.1t1'i':1 together 111.1e111I11i:
I-.I.ith pyroclastic
71.1111 . le11de. biotite,
hornblende, hiwtfte. green
:I-1'eei1 pyroxene
11:.'1'.::.I.e‘.1.I and
I1—
I..11.1 melanite.
111.15.111t

(2) LOWER LI' I..I11:I.' GISHU

'L1'1'11'e11 UASIN 13111111111111.
G11111t: PHONOLITE

Dthei'npe 111'
Outcrops 11h.'11111li1e are
of phonolite mm in
111‘e rare in thethe flat cultivated eettntt‘.
fittt .:LtitiI‘ttted country ..It' of the LiflS'il'l Ciiel'ttt
the. Uasin Gishu
plateau. the
plateau, he... exposures
the best neutering in
expreures occurring in thethe main I.I.".1: et'I-Ir1111'11eI1 draining
main watercourses pieteeu.
111.: plateau,
.ii'11i11ir1e the
.1111: in
and the upper
111 the .11' 1311:
I.1-.1111 of
111111.11 parts the bounding e11e111'11111-2nt11I1hereI
11.11111111113 ,escarpments where the soil:1'.:.IIL1
111.: ..I cover is 1'.I1 genera“.
generally
thin, at Turbo,
11:; at
thi11. as Bridge. Ziwa,
H.112}... Bridge,
11111111. Hoey's I‘.-'tLIib-en 11111-1
Zine. Moiben I.1:I'.Lt -
and Leseru,
~
.,The phenelite is
.l.1.1-':r phonolite
The lower '.'1pt11111i1ie and
1.1 aphanitic blue-black 1'in
1111.1 h111e—hteek with a
e.1l.11.1r. with
11 colour, concnoidal '.Ir
.1 e1.1111:11.1id111 or
splintery freeture. A
1plintery fracture.. iiL1'..'—1.Iihhi11g is
1'111e flow-ribbing
.I‘. fine .een in
i.I1 Seen .111 some eepewree and
11.11111: exposures I.'e.I.'ieles ere
1111.1 vesicles' 11.1.1rt.
are poorly
Phen1.1er;.-'.I1tI1 of
dereleeed. Phenocrysts'
developed. 111111.1—11rtheeleee are
111' soda-orthoclase' present but
are present are usually
but are It'ttftflSLlT'iT'lg
1.11111!!- measuring
1111.11.11. small,
up tr: 5
1.11:1 to r11111.. and
5 mm., 1".11‘E'ij.' show
111111 rarely preferred orientation
111.111' preferred that would
.11'ie111111iL'111 that indieete the
I.1-'11u1d 'indicate direction
the direction
~

...~
L
 32
32

of
of laya
lava flow.
fkJw. inIn thin
thin section.
section, specimens
specimens 34'4til
34/461 from
from Eldoret.
Eldoret, and
and 34 4E}? and
34/462 and 34 loll
34/468
the Sosiani
from the
from riyer two
Sosiani river north-west of
miles northwest
two miles Eldoret. the
of Eldoret, the phonolite is seen
phonolite is seen to haye aa
to have
pilotaxitic texture. with
pilotasitic texture, microphenocrysts of
with microphenocrysts elongated soda-orthoclase
of elongated soda—orthoclase inin aa groundmass
groundmass
of aegirine, eossyrite
patchy aegirine.
of patchy and kataphorite.
cossyrite and Abundant laths
kataphorite. Abundant soda-orthoclase ia
of soda-orthoclase
laths of in the
the
groundmass are
groundmass are associated with nepheline
associated with idiomorphs. Accessory
nepheline idiomorphs. minerals include
Accessory minerals include
granules
granules of of apatite
apatite and
and iron
iron ore.
ore.

t3: Berra UASINGISHU

(3) UPPER l’HoxoLtTF.
ts'xstts GtsHti PHONOLITE

The phonolites of
upper phonolites
The upper of the Liasin |Elisha
the Uasin Gishu plateau bounded by
are hounded
plateau are by aa west-facing
west-facing
escarpment extending
escarpment north-westward from
extending north—westward Eldoret towards
from Eldoret Further to
Leseru. Further
towards Leseru. to the
the
north
north the
the escarpment
escarpment diminishes
diminishes in in height
height and
and ceases
ceases to
to be
be aa topographic
topographic feature
feature about
about
four miles to
four miles south-east of
the south-east
to the of Nel's Bridge. Escarpments
Nel's Bridge. bounding the
Escarpments 'bounding upper phonolites
the upper phonolites
again seen
are again
are immediately to
seen immediately to the south of
the south Lake Sergoit.
of Lake Sergoit.

The
The upper
upper phonolites
phonolites areare similar
similar toto the
the lower
lower phonolites
phonolites withwith the
the exception
exception that
that
they are
they generally coarser
are generally contain larger
and contain
coarser and felspar phenocrysts.
larger felspar Specimens 345458
phenocrysts. Specimens 34/458
and 34/460 from
and 34;"4Ettl near Sergoit
from near Sergoit Rock and 345465
Rock and 34/465 fromfront near contain pheno-
Kamorin contain
near Kamorin pheno-
crysts
crysts of of soda—orthoclase
soda-orthoclase exceeding
exceeding 55 mm. mm. in in length.
length. The phencerysts often
The phenocrysts often show
show
lIfiarlsbad twinning and
Carlsbad twinning and are accompanied by
are accompanied by smaller phenocrysts of
smaller phenoerysts aegirine set
of aegirine in aa
set in
groundmass
groundmass of of felspar
felspar laths-
laths. Felspars
F~lspars of of the
the groundmass
groundmass are are arranged
arranged in in criss-cross
criss-cross oror
diyergent
divergent radial
radial groups
groups partly enclosed by
partly enclosed by small patches of
small patches of aegirine.
aegirine, eossyrite
cossyrite and
and kttttt~
kata-
phoritc. Some
phorite. Some rectangular
rectangular or or hexagonal isotropic interstices
hexagonal isotropic interstices maymay represent
represent altered
altered
nepheline.
nepheline, and and other parts of
other parts the grotindmass
of the groundmass show show aa colourless
colourless isotropic base of
isotropic base of
sodalite.
sodalite, analcite,
analcite, oror glass.
glass. accessory
Accessory minerals
minerals include
include scattered
scattered granules
granules of of iron
iron ore
ore
and
and small
small flakes
flakes of
of red—brown
red-brown strongly
strongly pleochroie
pleochroic biotite.
biotite.

These
These phonolites
phonolites probably
probably correspond
correspond to
to the Losuguta type
the Losuguta type phonolites
phonolites described
described
by uses. p.
Prior (1903,
by Prior 233}. and
p. 238), Smith {1931.
and Smith p. 236).
(1931, p. 236i-

4. Recent Superficial
4. Recent Deposits
Superficial Deposits
Red~brown earths
Red-brown deriyed from
earths derived laras of
the lavas
from the the Uasin
of the t.'asin Gishu
Gishu plateau coter most
plateau cover most
of the
of and eastern
central and
the central parts of
eastern parts the area.
of the covering the
Soils coyering
area. Soils phonolites are
the phonolites are compara—
compara-
tit'ely thin: they
tively thin; they drain freely. base
drain freely, have aa friable
friable texture.
texture, and
and nearnear the
the edges
edges of
of the plateau
the plateau
are liable
are to be
liable to easily eroded.
be easily The red
eroded. The earths are
red earths partly lateritixed
are partly often contain
and often
lateritized and contain
layers of
layers of cellular
cellular ironstone
ironstone or or "murram":
"murram"; this this isis located
located at at shallow
shallow depth
depth and
and isis
exeayated
excavated for for road
road surfacing
surfacing orer
over much
much of of the
the plateau.
plateau. Eon—calcareous
Non-calcareous black
black or
or grey
grey
clays
clays occur
occur onon the
the plateau in shallow
plateau in shallow yalleys
valleys and
and areas
areas of poor drainage.
of poor drainage.

In the
In the northern and western
northern and parts of
western parts the area
of the area pink or brown
pink or soils coyei
sandy soils
brown sandy cover
the Basement
the System rocks;
Basement System they are
rocks: they generally lighter
are generally in texture
lighter in and less
texture and fertile than
less fertile than
the plateau
the plateau soils.
soils. The
The soil
soil profile
profile is
is generally thin but
generally thin but deepens
deepens user the talus
over the talus accumula—
accumula-
tions at
tions the western
at the foot of
western foot the Cherangani
of the hills.
Cherangani hills.

1" I—ST RL'C TURE

VI-8TRUCTURE
chief structural
The chief
The features of
structural features the area
of the are shown
area are in Fig.
shown in They can
ti. They
Fig. 6. cart be con—
be con-
yenlently divided
veniently into structures
diyided into impressed on
structures impressed on the Basement System
the Basement rocks in
System rocks Precam-
in Precam-
brian times
brian which developed
those which
and those
times and developed much later during
much later Pleistocene rift
during Pleistocene The
faulting. The
rift faulting.
Precambrian structures are
Precambrian structures complex, and
are complex. and further complicated in
further complicated in the north—east by
the north-east by
normal faulting
normal near to
faulting near the Rift
to the ‘y'alley.
Rift Valley.

-~
 r-_-'_'.'._'_.H_ _""'_._ __ :_

33
,°00' N

i~I
.l

~
~ ~
\. .0
10

,,\! 6
" "-..3S
10"

. TVP2 .
, '" '
......

ELDORET
. ,...,
0
.
, "" . '"
. TVP2' ...,

SCALE O'30'N
10 15MILES
, ,

T--.:::- ' Zelcoer

TVP; Liesm G,shu
Upper Uasln Gish-a Phonolite
:‘no-‘e-i ta --
fO Plunge
Plunge o4
01 lee-atroc-
lineation

~/'
Eat".
| . :Tvp,. Lem-Er Uasln
Lower
Basement
__*
' Boundary
Shoe-o. te
'Slshu Phonolite
Ljasm Gishu

L- . .
_'.-_.ste'r‘- '3':‘-'_'-
System

(approx.
':."‘Ie.!'er'noar= metasediments
Cherangan,
rocks
['aoorox )| of base
ease 01
"tetasod -‘-':—'ar-'._;.
or
..-<'

......
Flow
'— |
r ow :as-r-rs vest-ca
Flow layers vertIcal
Prelerred orientation
Preferred orrentatlon as
onenocrysts
phenocrysts
of
d-p
-.-.-It-"I dIp
lay-firs wIth
F'ow layers

-<30 D,p:1: err-Li

and strme
strrke or
of what
foliatIon
.- ,_I

-A"" Faults "o'r-

Faults. norn,al:-

~m" :r_: ‘ol:a".

VertIcal lollationon --- Fauflgi H
Faults, Pg;-
hInge
*r-rusrsxw H" dIp
or and
and direction
d rect o"
~cw" ‘_
32"‘3 of
r.
Strike.
o” folIation,
o r_.lTiC.-|"_ dIp
i: _
o-L; not _
not sl‘ossr:
shown of
'-.-'
~
thrust
'. 'u .- I.
Thrusts,wlth
--.; l' L - I: I

Fig. 6-Structural
Fig. fi-—5truet‘ural map
map of the Eldoret
of the Eldoret area. area.

1. Structures
1. in the
Structures in Basement System
the Basement System
.,s (l) LITHOLOGICAL
(1) Li't‘ttoLooitii-sL BOUNDARIES
BtfitL'NDAREES AND
aso REGIONAL
REGIONAL TREND
TREND
Distinct lithological
Distinct lithological boundaries
boundaries are
are only clearly
only clearly seen
seen inin the
the rocks
rocks of
of the
the southern
southern
lCherr-ungant hills
Cherangani hills where
where. the
the. contacts
contacts ofof distinct marker
distinct marker beds,
beds. such
such as
as quartzites
quartzites andano
graphitic schists,
graphitic schists, can
can be
be followed
followed across
across country for
country considerable distances.
for considerable distances. AA. strongly
strongly
~ developed t‘oliation in the neighbouring
neighbouring gneisses
gneis~es oror schists usually lies
lies parallel
parallel toto the
the
I developed foliation in the schists usually

~
 3—1
34

1.'1'111111131': of
contacts 1‘:1"1‘11E
the marker 1111-" is
11111'1._-'1:-11:. and
111111'11E1' horizons EE1111‘L11E111 with
1:1 coincident 13111111111151. It
111 11.51111'11 bedding.
1.'-.1111 original 1111111111511 a11
11 follows
11111111E1'i5.'- 11131111 in
northerly-trend 111 the 111g11 ridge
1111'. high' EEu1111'5.-' between
1'1115.:E country K111111111 and
1.1-E111'EE11 Kapsiliat C'1'1E111L11'1111111. where
111111 Chemurokoi, 1.'11E1'E
111-1111111111 dips
E:1E1E1'1511 foliation
easterly 1111111: of b6111"fl1.‘1f1315""111£1
1:11 between 35° and 50° :11'1'1'11'E
are maintained 1111'EE area.
1'.-'1'1E 1' a1-1 large
11111111111111E1'1' over '.11'E11. In1:1
E111111'11:11 111E 11' 1 E111— 11.1111'1L111-1 11:111111115 111E
contrast the meta-sediments forming the Cherangani foothills north of Kapserwa strike CE:15. '11E11111111'11111111111 11E1'11: 111' KEpEE1'1'1'11 :111'111E
1111.'-'111E:11-"E:11-——:-'-.I1'111111-L'.'.1:'.1 and
north-west-south-east 111:1 to
111111 dip 111:11'1'1'1— E11:11. at
111 E north-east
115 the 31.1". The
11121111111 30°.
1:1 about T11E two 1 131711.111.
511'11-1E trends,
115-111 strike
11111111111111.1111'11111: 111': E . 111EE1 1E1 111E [111E 111
oblique to each other, meet on the line of the Chepsera valley, which marks the axis of 111E C11EEEE1'11 1—':111E5.'- 1:'111Eh 11111111: 1111': 11:11:. 111'
a1: 5.51' E111 easterly-dipping
great 1E1:11L'1'11'-115'11"1515111111111. thrust.
T11 the
To 111E11E111
west and 111111111-11E111 of
11111.1 south-west 111 the C1E1L11'E1:.11 hills
111E Cherangani 11111::111'111E 5.51“. 11111.11.
the granodioritic 11115.5:1'1111111-1'
11'1d migmatitic
11111 and
EEEEEEEE in
1111:1111 exposed
rocks 1'11 the K111111111EE and
"'~1'EE111. Kipkarren
1'1'1E Nzoia, 1'11'1E51: do
511111521511 valleys
1111.11 Sosiani EE not 11111111115
1:111:111111 sharply
1111:: contain
11'1'11.1155:L11 types
111E1111g111511111711E lithological
distinguishable 151pE1-1 with1111-11 easily 13111111111".1'1E:1 The
111111:1111-1131E boundaries.
E11.E.1151' mappable T11E strike 11E 131:1
111111-11: here is
111111E111E11 by
indicated 1151' an fi-1111.—.-.'111L-111E11 often
111111111111E1 flow-foliation,
11.51 indistinct :111111EE1 to'
E1":E1'1 subject 1.1'1 localized 1'1'E1'11 1111'.
1.11:1'1111...L1 f!TOmthe
111E 111'1-EEE1 deviiiitions
11 E1-1‘1'11-15-E -1. -— south-east
north-west 1rE11d. Dark
1'E5.511.'111111 trend.
1111:1111—1111:11 regional 1311111111151:1.'.11"'.'1E1'1111111'1:1.
1J1'1111 schlieren or xenoliths, and 111111 thin 15.11111. 11."
111111 biotitic
11111511E:1 are
stripes 111E generally E11111E111E1‘1 in
:‘.5E11E1'11115.-' elongated 11115 11111111111151
111 this direction and :‘1E1'1'E to
111111 serve E111151111511'E the
11‘: emphasize 1111'EE11E11:1|
1|1E. directional
11'E1111 of
trend fiDE-EEfE'J111iIL11'JE‘1. which
E1' flow-foliation, 11111111111115 dips
11111111111 invariably
11.111 11'] almost E11111 or
115E east
11:11.51'111'111: the
11153111 ,towards 1111.5:"1—E1-'1:'L1.
111' north-east.

|-'1".11_1.'1:.
1'2] FOLDS
(2)
FE1111115E. is
Folding 111:1}:111151'E1i in
'EEE: displayed
1.5. best 1'11 the 111'11'111—E1151E1'11 part
111E north-eastern 1111111 of 111: the '.1'1'1E1E. clearly
111'EL1 where
[111: area 11E1"'1:1E11
E1E111'151' defined
111E11'1-11Edi111E15.1:11'5.—' horizons
meta-sedimentary 15111111111111 are Et'EEEE: in
111'E present 111 the {ThErEEgEE-i hills.
1i Cherangani 11111.;1.HE1'EHere folding 1111111111; af E1' the 1111-
EEE: can
beds E1111 be :EEE on
11E seen E11: all :'.E1:‘LE:1 from
1111 scales 111.1111 small 1'=1.1111111 each
11111111 folds 111E11:1111i :15: a11 few
E11E11 measuring 111E1E11: across
1'1—11".: inches 11131111.: to 1E
1111111111111 sized
medium 111E111111E1111E in
113111111: measurable
EiEEd flexures 1'EE1. Larger
1'11 feet. 1-111'EE1 falds 1'11111: are 11E1111E111E11'as a11 result
111'E delineated 1'E'-:11111 of 111'
boundary 11111515511151. 'IhE
11E111'11'11'11'5' mapping. ~he major 11111jE1' fold 5:11111E1'11 is
111111 pattern :'E1"1EE1E1'1 in
1:1 reflected 111E 511'
1'11 ,the style51'11: of 1'11'"11'11111_11'
minor folds 1'1'111'11.
'.1'111Eh are
which E1'E11111'11E11 towards
1'EpE1—11E1115' overturned
111E repeatedly 11111-11111: the 111E west, 11'E2111'. or111' south-west, :E 111111 all
:111111h—'.:.'E:'.'1_. So'that 11:E limbs
111] the 11111111:
1111) to'
dip 11': the E1111 ar
111E east 11111'1'11-EE11. Dips
111' north-east. D1511: in 1:1 the 1E1—'E1':'1E limbs
111E reverse 1111111: are E1EE511E1' than
111E steeper 1111111 those 11111::E in 11: the111E
:111511EE111' normal
adjacent 111111111. and
11111111111 limbs, 111111 in 111 many 1111111111EEE. the
15:11:15.5 instances 1E1'E1':'.-.".11 limb
111E reversed 1111111 in 111 the 111E minar E15111: is
1:'11'111'11' falds 1:1
1"111E1111111E1'1 or
attenuated E11111111111E11 by
E1 eliminated EhE111'11'15'.5 on
1151' shearing E11 eastward dipEiEE surfaces
E11:.11'.'1'111'11 dipping 1.111.111: parallel p111'1111E1 to' LE axial
11.: the 11.111111
E11111E of
plane 111E fold
E1' the 1131111E VI
1'1'1111 (Plate {_1-"1'1. The
‘1'1 (a». 11'1115'1'11115'E1'
'1'1111'. majority 1:1E:1E folds
of these 1111:1111. were E1'111EE1151'EEE1'111EEE
15L'E1'E evidently produced
by 5.11:: on
1'1E' 11111'111.slip
1:15.- flexural 131151C1‘151"E1.11I.11‘11[15;5 movement
E111 easterly-dipping 111E'1'1'111E111 planes. 51|1111E:1. A 5‘1 similar 51111111111 is
:111'11'1111' piiittern 1:: 1:1111E111E1'1
indicated
by 1'11111:. of
1:155 folds 111111111::.1E11:_: ,thus
1E1.51-1'111111 dimensions;
111' regional 11111211 a11 single
11111:. where 11E1'1'EE11 is
1'11:11'11E1' horizon
51115.5]E marker 1:'. TEEE11=-E1'1
repeated across 11E1'E:1:1
11'1E :11'111'E 1111: 1111111111111: 1111 111511 E11:'1111-111'11:1_.
the strike the outcrops all dip eastwards, but the infeITed reverse limb is comparatively E:11 1:1E. 11'11E11'E11 1"E1'E1‘:1E. 1111111 1:' . 1E11'1511.:1L.L-5.'EI5L
:. EEE. andaften
steep, 111111 1111E11 terminated against. acutely
1E1'1'1'11111'11E11 against 111:111111E11 rocks
11E111EI515 distorted 1'EEI'LE. of 11111E1'E111 type,
1.11 different 1111111E1111'1E:1
151-51E. sometimes
E11111111111n55. 11111E11 11111EEEE E1 111111111
containing rolled masses or thrust melange, as on ,the eastern slopes of Geben 1111111111151: 11:: E11 115E E1151E111 5111511111 1111' 1UE‘EEE ya 5.111
.‘1'11151'1'11E. and
MayotO', 111111 onE11 the 111111111E1'1'1 face
111E southern fEEE of (31111111111511. Due
Ef Garamaso. DEE to 1E the 11111::1'E of
111E nature 1111' the 111E larger11115.1E1' folds fE111':1
the 11Er11'1111 limbs
111E. normal E:11E1'Ep over
11111111: autcrop grEEt areas
E'.-'E1' great 111E115: in 111111111 E111111L-"11'd—11'1E111'1E11
111 broad eastward-inclined dip 1111'_1'-.::E:1. the
111E slopes, 1111:.
1111p1'EEE1E11 is
1:1:E11111 impressian
overall EEE of
1:1 one EEinEidEEEE be!tween
111' coincidence 1'.-11111111E11 and
1.5.11111EE1'1 foliation 'EEd-fling.
111111 bedding.

'1'11E arched
The 1111151EE of
ErE11E1'1 hinges 1111111. of
1711' falds 1n1E1E1E11i111E dimensions
111' intermediate 111111E1151E115 are 111E to' 1E be :1EE11 at
11E seen 1'11 the 5.1111111—
111E. south-
E1'1'1 E1111
ern end of C1E1'1E11 5.5151
Ef Geben 1'1-"1115.1E1E. on
ya Mayota, Jariget 111111
E11 111115.1E1 'EEtWEEE KEEEEEEE
and between Kapserwa and K151111111E1. The
1111111 Kipkoitet. T111.-
11"111511'1'1 as
1'1'EIEE known
ridge JEI'1gE1.1E
11:1 Jariget, is E11111:113]
co-axial with 5.511111 11a small 11111111: 1111E :11:
11'1'E1'1111'11E11 anticline
:11'11111'1 overturned So' that .-'E:'.5L'1E1'111-'E
.11111 respective
1'11I11Ed
folded beds 111111E1'Ep 111
111E111. autcrop crescentic 1111111
in E1E:'.EE1111E form EEIEEE
across the 1hEE1'EE-1
cresit of 111' the hErE. 11:1
1'1'15E5E; here,
111E 1.'ridge; as at111 GEE-E11
Geben
5'11 111115111111.
ya Mayoto, the 111E1En'1111511h11: layers
111E metamorphic competency 1111111151
different 1:1'1111111E1E1'1E511
show 1111'1'E1E1'11
11151'E1'E .1h 11111111115. 5E
during folding, so 111Ethe
1111111: 1E:5.i:'.1111'11
more 11E1'1'1111E11111'E beds
resistant hornblendic E111E1'EE in
111E111 ,outcrop E11115E11 slabs,
55En1155 curved
111 gently 5111115. but 111E 1111E11—'EE111g
1.1111 the intervening
EEE1E11111E: 11E5L5EIEE
1115.5E1':'. sometimes
layers develop drag-folds 1111:1151-1111115 or 111 minor 31111111111113.1111. where
111111111 crenulations E1111-'111111'E is
11'11E1'E curvature 11E111E
1:'. acute
1'F'1111E
(Plate '11-'11.VII, 11111.
(a».
.111
In the 11'11'.‘ Turbo 111111-1'1'111'111 in
-'11'E11 flow-folds
"1'111'bE L'area 11: 111E 1111g11111111EE are
the ,migmatites 11'1'E5.511111r: the
L'-11'E irregular; 75111111111 amphi-
111E Ndalat 1.51111511111-
111'1‘111E is,
bolite is. however, 1'11111E11 into
11E11'E11Er. folded 1111E an 115.511E1111E of
EpEn syncline
1111 open 511111151E.
11111111E1151' plunge.
111' northerly

THEE-.1111
13'} THRusTS
(3)
511111: of
1E'11-'E:'11111:1 parts
1111:. lowermost
The 1111: Cherangani
E1" the :111EEEEEIEI1 and
111E111—:1E111.11'1E111LE.1'5L' succession
ChErEngani meta-sedimentary 1111111:
111E more
111111 the
h1111'1EgE11EEu11. area
homogeneous 111E11 of grEEE111'11111E and
Ef granodiarite 1515111515 to
11:15.111111111E lying
End migmatite 1E the111E west, 11'E:11. is 111151'E1'EE11 by
1:1 traversed 1351' a11
:1E11E1'. E1 111111111 11111::11—15.1111E11 fElIEwiEg 11 11E1'1h-11'E51E1'15'
series of major thrust-zones follawing a narth-westerly or north-south direction and Er 1' 1 1' 1 111'1 - 3E11111 1:111EE111111 111111
dipping HERE in
1:15.5111'111'115. Rocks
111515111115 eastwards. 11111151—EEEEE are
111E thrust-z{)nes
11: the fE1111E11111'1E
EIEEE151' foliated;
111E closely the more 111551E111111
111E1'E mylonitic
15.5511E11 are
types. 111151.151 111111 o£ten
111E flaggy_and 111111112p in
EftEE autcrop (11:51: 11:11:11. upon
111 dip-slabs 111111211 bdth
111::E1'1 which 1111111 strike :111'1kE and 111E
E1511 1111' the
111111 dipq:f
5111..'111-1E111111E1'1 can
:she;ar~foliation E1111 be prEEIEE151'1'1'1E11'11111
11E. precisely me~sllred (P.1111E VIII,
'E11 (plate I11'III.1f_.:1"_}.'1.
(a». The 111111111: have
T111: thrusts EEEE
11115.5E .been
E11111E11 S'0
d111E1'E1111111151' erode<;l
differentially EE their E11EE are
1hE11' axes 111E usually fD11DWE‘d by
11511111151 foHoiWed 1:155 valleys, End E111E1Epr: 'Of
1=E]1E5.':5.. andouocrops Ef
111ET-E1'D1‘E tend
1115-'1E1111E therefore
mylanite 1E1111 to 11': be EupErfiEiEl deposits.
1:151 superficial
1111111111111 by
'EE masked dEpEsits. .

~........
 35

Ln
LU
'1 he thrust-zanes
The thrust—xenes change
change inin character
character in ineying fram
inmaving frein cast te west
east to. west acress
acrass thethe area;
area;
the
the easternmest
easternmast thruststhrusts at
at Sembeywa
Semheywa. and Chemurekei are
and Chemurakai are zen-es
zanes af ef streng piastie
strang plastic
defermatien assaciated
defarmation asseciated with felding. They
with falding. They havehave been
been drawn
drawn an en the
the map
map where
is here the
the
reyerse limbs
reverse limbs af ef majar
ntajer falds
felds wauld
weuld ,be he expected
expected to.tn accur
eccur andand represent
represent axial-plane
axiai-plane
slips aieng w.
slips alang ieh eyerturned
which averturned anticiines
anticlines haye. been <thrust
have been thrust westwards
west-wards eyer
aver adjacent
adjacent
'¥' synciines. The.
synclines. The {T'hepsera
Chepsera and tit-reserwa thrusts
and Kapserwa leeated further
thrusts located further teto. the west. exhibit
the west, exhibit aa
less plastic
less plastic style
styie af
ef deformatian;
defermatien: like iike the
the thrusts
thrusts traversing
trayersing granodiarite
grantidierite and
and migmatite
inigniatite

l in the
in
has
the Turbe—Kipkarren
Turba-Kipkarrenregian
has suffered
suffered no.
The
ne para-
para- er
regien they
they centairt cataeiastie rocks
contain cataclastic
pest-teetenie recrystaiiizatien.
'Or past-tectanic recrystallizatian.
reeks inoluding
including mylanite
ntylenite which
which

The easterly
easterly inclinatien
inclinatian ef of thrust-planes
thrust-planes tencis
tends te irtcrease in
to. increase in the
the western par: ef
western part af
the area.
the area, se
so. that in maving
that in ttteying fram
frem what
what is
is eyidentiy
evidently aa falded
felded .superinctttribcn-t
superincumbent series tn 3.a
series to.
ntassiye
massive crystalline
crystalline basement.
basement, the the thrusts
thrusts steepcrt
steepen inte upthrusts. aa phenemena
into. upthrusts, phenamena Jire— fre-
quentiy asseciated
quently with the
assaciated with heundaries af
the baundaries ef great feided mauntain
grea.t fa,lded n'niuntnin chains
cnains tide hitter-
(de Sitter,
1956. p.
1956, p. 233].
235).
tel The
(a) Chepsera Thrust
The fifteen-art Thrust
The
The Chepsera thrustuxene. aver
Chepsera thrust-zane, eyer aa mile
mile inin width.
width, extends
extends nerthts'ards
narthwards framfrem Kitisagat
Kaisagat
aleng the
alang the Chepsera
Chepsera yaliey
valley tn 'lienten at.
to. Ten,ten at the
the nerthern
narthern edge
edge nf the area.
of the area. Black tlinty
Black flinty
pru'phyreclastie
porphyraclastic mylenites eutcrep tn
mylanites autcrap to the
the nest
west nf
af the .‘yIeiben—Chebnrerita rent-id
the Maiben-Chebarorua raad ciese
dase
beneath the
beneath the edge ef the
edge 'Of the plateau phenelitc en
plateau phanalite the snuth
an the sauth side
side ef
'Of the Haeia valley,
the Nzaia yalley. and
and
further eutcreps
further autcraps cart
can bebe seen aheut ane
seen wbaut cine mile
mile seuth—east
south-east af ef Kakarawa
Knkeren'a fFlate
(Plate T. [Chi].
V, (b»,
where
where thethe myienites
mylanites strike
strike 1D":
100 east ef nerth.
east af narth, and
and dip
dip at 3ft" to.
at 300 tn the
the east.
east. .
Te the west
To. ,the west ef the thrust,
'Of the thrust. the
the. ridges
ridges ef of the
the lCherangani J'etititiils strike
Cherangani foothills eblietieiy
strike 'Obliquely
inte the
into. western sides
the western sides ef the Chepsera
'Of,the 'alley. but
Chepsera valley: but to
tn the
the east
east the
the regienai strike is
regianal strike is such
such
that the
that the underthrust.
underthrust series is cyidently
series is evidently truncated
truncated by by tire
the dyer-riding reeks ef
over.-riding rocks {fhepkast'a
of Chepkawa
and Sagetie.
and Sagatia.
._iI-fl(b)
..'-'__:| The K’rtps‘r—‘rtt-‘rr Thrust
The Kapserwa Threat”
a series
A series 'Ofef thrusts
thrusts fellews
faHaws the the margins
margins 'Of ef tirethe seuth-westeriy
sauth-westerly facing
facing Cherangani
Cherangani
feethills near
faothills Hapserwa. Deep
near Kapserwa. Deep valleys yaileys ,cutting
cutting acrassacrtiss the
the regianal
regienal strike
strike 'reveal
reyeai dipdip
sectiens demenstrating that
sectians demanstrating that the
the ribbed ribbed upland upland is is aa thrust-frent.
thrust-front. The
The Inserts-t
Lasarua riverriyer and
and
its tributaries
its tributaries plunge
plunge in in cascades
cascades and rapids nyer
and rapids augenii'ereus cataclasites
aver augeniferaus eataclasites and mylenites
and my1anites
dipping
dipping uniferntiy
unifarmly rewards
tawards thethe ENE. ENE. and berth—east: similar
and narth-east; similar racks
reeks can
can be be fallawed
fnilewed
seuth-eastwards beneath
sauth-eastwards beneath the the seuthern
sauthern slapes slepes ef Kapserwa where
'OfKapserwa the mean
where the mean strike
strike ef the
'Ofthe
thrust—eerie
thrust-zane is is '25;
250 west
west efaf nnrth.
narth, and and dip dip measure:
measurements tents an
en mylanites
ntyienites inin seycrai
several diff-er—
differ-
ent lacalities
ent lecaiities vary
yary between
between 2%”280 and and 30° iitft'i east.
east.
:1 thick
A thick apren et superficiai soil
apran 'Ofsuperficial seii and
and gray-e1 carried frent
gravel carried fram the the faathills
fenthiils masks
masks much much
ef the
'Of the bedrock
hedrecic between
her-ween Kapserwa
Kapscrt—ya and and the Nzeia river,
the Nzoia riyer. but
but. the
the racks
reeks seen
seen in stream—
in stream-
cuttings clese
cuttings clase te
to. the
the feet
foat ef the hills
af the hills are mylenitic. se
are mylanitic, so the thrust-xene prebably
the thrust-zane probably extends
extends
beneath the
beneath the flaar
fiber 'Of
nf the T's'zeia valley
the Nzaia yalley tierth-eest
narth-weSt ef af Tesetti's Drift. Since
Tasetti's Drift. Since the the gene
zail1e
separates differentiated
separates differentiated meta-sediments
meta-sediments af ef the
the Cherangani
Cherangani hills hills fram
frem granodiarites
grartedierites and and
rnigntatites 'Occurring
migmatites eccurring further
further tore the
the west. it is
west, it is possihly
pessibly aa thrList—uncenfermity penetrating
thrust-unconfarmity penetrating
deeply into.
deeply inte the
the crust
crust which
which has
has pravided
preyided an ayenue far
an avenue fer peridatite
peridetite intrusion
intrusien (p.
{'_p. 27).
2?].

{cl The
(c) if'fre Matunda
i'irfrrtrrrrri’rr Thrust
Ti'irrrs't‘
i_incated mylanitic
Lineated mylenitic gneisses
gneisses striking ENE-“v". dip
striking NNW. dip eastwards
eastwards at
at apprnxintately ii in
approximately 5° in
the Little
the Little Nzaia
Hzeia river
riyer about
abettt five
five miles
mites dawnsteam
dewnstcam from
frem Ziwa sisal factary.
Ziwa sisal factery. TheThe thrust-
thrust-
xene to.
zane te which
which they
they belang
beleng passes
passes narthwards
nerthwards benealth
beneath the
the phanalite
phnnelite and trends tawards
and trends rewards
Heeyis Bridge.
Haey's Bridge. Judging
Judging by by the intensity and
the intensity and width
width afef ntyienitixatien
mylonitizatian it it is net sti
is not so.
intpertant aa structure
impartant structure asas the preyinusly described
the previO'llSly described thrusts-
thrusts.
i
(d) The Turbo
frf} The Thrust
Trrrhe Thrust
This is aa
This is pewcrful
powerful thrust
thrust trayersing the Turbe
traversing the Turbo granedierite and niigmatite.
granodiorite and migmatite. 'l'he
The
etfccts can
effects can be
be seen far
seen fer widths
widths af
ef eyer
aver aa mile,
mite. and
and the trend 'Of
the trend ef the
the eastward-dipping
eastward-dipping
~ ) shears can
shears can be
be fellewed far
fallawed fer aa distance
distance 'Of
cf 12
12 miles
rniies from
frem the
the sauthern
seuthern margin
margin 'Of
ef the
the
I

....
 --- -

366

Li-J
area. to
area, to aa point
point oneone mile
mile north-east
north—east of of Turbo.
Turbo where where it it disappears
disappears beneath
beneath the the phonolite.
phonolite.
The main
The main thrust-zone
thrust-zone emerges
emerges no.rth-westwards
north—westwards from from 'beneath
beneath the the phonalite
phonolite about about two two
miles west
miles west af of Hemstead's
I-Iemstead's Bridge,
Bridge. continuing
eontinuing DUt out af of the
the area
area ,tawards
towards Maunt .‘tloant Eigan,
Efgon.
and may
and may ultimately connect with
ultimately connect thrust mapped
with ait thrust mapped on on the Kenya-Uganda boundary
the Kenya-Uganda boundz-iry
north af
north of MDunt
Mount Elgan Elgon (Searle,
t'Searle- 1952,
WEE. p. p. 75).
T33}.
South
South of of Turbo
Turbo. the eataelasites in
the cataclasites in the thrust-zone ,trend
the thrust-rone trend in in aa north-so.uth
north—south direction.
direction,
oblique to.
oblique the regional
to the strike Df
regional strike of thethe crystalline basement. so
crystalline basement, foliation Df
that fQliatiDn
so that the.
of the
andet‘ormed rocks
undeformed progressiyety into.
swings progressively
roetts swings into the thrust—line. Near
the thrust-line. Near ,thethe southern
sDuthern margin margin
area the
the area
of the
of the weSlternmost part of
'-.yesternmr_i:st part zone of
the zone
of the deformation is
of defarmation seen in
is seen in. aa deep valley-
deep valley
to the
to. west of
the west Kabien'iet. where
of Kabiemet, slabs of
n’iassis-‘e. slabs
where massive of grey strilte 2r
eataelasite strike
grey cataclasite 33" easteast Qfof
north. and
north, and dipdip 40°40" ESE. Deformation is
ESE. Deform3Jtion intense to
more intense
is mare to the east of
the east Habiemet. where
of Kaibiemet, where
thin sheets on
mylonitie sheets
thin mylonitic strike and
similar strike
on similar and dip interfoliated with
are interfDliated
dip are with rocks displaying
rocks displaying
strong eastward—plunging lineatians
strong eastward-plunging [Plate VIII,
lineations {Plate rods or
tint}: rods
\"III. (a)); mullions of
or mulliDns of the same
the same
orientation are
orien,tation deyeloped in
rre developed zone of
the zone
in the masimum mDvement
of maximum movement (plate tPlate VIII, The
tell. The
VIII. (b)).
thrust continues
thrust northwards between
continues narthwards Raptabei and
.etween Kaptabei Ndalat: black
and Ndalat; trtylonites of
fitnty mylonites
bin-cl; flinty of
easterly dip
easterly dip cancan be seen about
be seen miles west
two miles
about two. west. of Ndalat. and
of Ndalat, gneisses with
mylonitie ~eisses
and mylonitic with
tale—actinolite schists
talc-actinQlite outcrop on
sehists outcrop slopes af
the slopes
on the marking the
hilloelt marking
small hillock
of aa small extreme
the extreme
north-western carner
nQrth-wes,tern eorner of Ndalat. FrQm
of Ndalat. From here here thethe thrust runs into.
thrust runs Sosiani valley
the Sosiani
into the yaiiey andand
eventually crosses the
eyentually crosses about Dne
river about
Sergoit river
the SergQit mile east
one mile east of Turbo. Here
of Turbo. microeline
Here microoHne
augen-gneisses and
augen~gneisses mylonites dip
and mylonites dip at at 40° to ,the
all]: ,to. east. and
he east, and canean be followed into.
be fallowed into thethe
vaHey north of
valley north Crosford Bridge
of Croxford Bridge wherewhere they they disappear beneath the
disappear beneath phonolite. A
the phonQlite. fit
similar eastward dip
similar eastward maintained in
is maintained
dip is sequence of
thick sequence
in aa thick of augen gneisses and
augen gneisses mylouites
and mylDnites
esposed in
exposed the NZDia
in the river to.
Nzoia river west af
the west
to the Hemstead’s Bridge,
of Hemstead's representing the
Bridge. representing con-
t_e can-
tinuation Qf
tinuatiDn of the Turbo thrust north
the TUl"bQthrust north Df the phDnDlite
of the outerop.
phonolite outcrDp.

The Kipkarren
lit-"l The
{e) Thrust
Kipkrtrrr-flt Thrust
.‘N'ear its
Near eonfiuenee with
its confluence the Sosiani
with the riyer at
Sosiani river 1IItthe margin of
western margin
the western the area
of the the
area the
river fDllows
Kipltarren river
Kipkarren dark n'iylonitie
of dark
zone of
follows aa zone gneisses and
mylonitic gneisses blastomylonites striking
and blastQmylonites striking
mirth-west south—east and
nDrth-west-south-east dipping at
and dipping about 40°
a'. about the north-east.
to the
40" to. thrust-zDne in
The thrust—zone
north-east. The in
which they
which eatends south-eastwards
outcrop extends
they outcrop sDuth-eastwards hetween Kaptabei and
between Kaptabei and the Kipltarren
the Kipkarren
yalley and
valley and is distinguished by
is distinguished presence of
the presence
by the Df muscovite and actinolitic
phyllonites and
moseorite phyllonites actinolitic
\ schists.
schisits.
I
(4) Fatftrs
Mons-1st FAULTS
{f—ll NORMAL
displacements of
Small displacements
Small the phDnolite
of the late Tertiary
by; late
phonolite ,by or Pleistocene
Tertiary or can be
faults can
Pleistocene faults be
seen in
seen the esearpments
in the Moiben and
betw-‘een MDiben
escarpments between and Hoey's Bridge, near
Hoey-‘s Bridge, Turbo. and
near Turbo and also
also
north-west of
north-west Falls. The
Selby Falls.
of Selby fault-planes are
The fault-planes breeciated and
are brecciated silieified. and
and silicified, and thethe
disrupted lava
disrupted is often
lat-"a is strongly stained
often strongly with irDn
stained with oxides. but
iron Dxides, but the rrioy-‘en'tents
vertical movements
the vertical
seldom exceed
int-'oly'ed seldam
involved feet.
20 feet.
exceed 20
Faulting on
Faulting larger scale
on aa larger is evident
seale is close ,to.
evident. close the bDundaries
to the of the
boundaries of ‘s'alley.
Rift Valley,
the Rift
and three of
and three the fractures
of the fraotures deserve separate mention.
desert-e separate mentiDn.
tit-n The Karuna
(a) The F rtm’r
Ker-nun Fault
A pDwerful
A pot-serful hinge-fault
hinge-fault extends
extends for
far aa distance
distance of of over
over 20EU miles
miles from ti e upper
from the upper
Moiben near Chebara
yalley near
Moibeni valley Chebara to to aa point about sis
point about six miles to the
miles to of Sergei:
south of
the south Rock.
SergDit Rock.
passes close
lt passes
It to the
close to east of
the east Karuna. and
of Karuna, and in that area
in that cleaved phonolites
area cleaved are down—
phDnol1tes are dDwn-
thrown to
thrown the east
to the quartzites of
against quartzites
east against of the
the Basement System. Steeply-dipping
Basement System. Steeply-dipping
haematite breccias
haematite the position
marls the
breeeias mark of the
pos1tion of fault in
the fault the .‘vloiben
in the river between
Moiben riyer Kapsiliat
between Kapsiliat
and Kibuswa.
and Kibuswa.
Faulting of
Faulting Df this itirtd accounts
this kind for the
accounts fDr thickness of
great thickness
the great of phonolite
phonolite seen in the
seen in upper
the upper
part of
part Tambach escarpment
the 'latttbaeh
of the two miles
escarpment two east of
miles east the present
Qf the present area; the sub—Miocene
area: the sub-Miocene
surface has been
surface has been stepped dDwn towards
stepped down the Rift
towards the Valley, near
Rift \-"'alley-'. near Elgeyo. enabling preserva-
ElgeYD, enabling preserva-
tion of
tion the upper
of the upper phonDlite
phonolite onon aa narrow
narrow shoulder
shoulder aboveabove thethe main
main escarpment.
escarpment. The The
Haruna fault
Karuna probably has
fault probably an eastward
has an exceeding 20d
downthrDw esceeo‘ing
eastward downthrow feet in
200 feet its southern
in its sDuthern
portien.
pDrtion.- -

=
[
 II:

37

“-hJ
so
[ht The
(b) The Moiben
ill-'1 titt'hett Fault
Patti"!
Two miles
Two miles east
east of Moiben- the
of Moiben, the flat
hat plateau
plateau of phonolite talls
of phonolite falls steeply
steeply assay
away to to the
the
Arobobuteh valley
Arobobutch at aa straight
y:113-. at tr.'I'ttl '.g escarpment.
I'Ioz':h-south trending
straight north-south Here the
esearpme nt Here the base the
of the
base of
phonolite is
phonolite is seen
seen atat aa height
height ot‘ of tsTSt't t'eet. whilst
6,750 feet, yy'hiist on the eastern
on the eastern side
side ofof the
the yalley it
valley it
stands at
stands at an
an altitude
altitude of? Hill feet
of 7,100 1 eet on the. up
on the upthron'n
thrown side. side of
of an interyet‘ting fault,
an intervening fault. Whieh
which
ean be
can be traeed
traced southtyartls
southwards for t"1~t 1'a1 distance
distance of of 1515' miles
miles toto where
yyhere itit converges
eot'tyerges onon the
the
tsaruna fault
Karuna east of
fault east of Sergoit
Sergoit Rock.
Roek.

The Moiben
The ls'loib en andand KarunaKat‘ttna faults
faults throw throw in in opposite
t‘tppt‘tsite dit'eetit'ms
directions andand hence
hence bound
bound.a
'tart 1111 wedge-shaped
narrow yy'etlge-s2eh 1p..- at strip ol Basement
strip of ['31-'Iset'112ttt System
System rocks,
rocks. flanked
flanked on on both
both sides
sides byb" phono-
ph1~t'.1"-—
lite. Eaeh
Each 1f of ttheeta; Ilt s has
has aa northerly
hrte.l'1 'trend. rotighly parallel
parallel- to the larger
la: ger north-south
I-ottt—t south
1......

lite. faults trend, rougWy to the

trending rift
trending rilt valley
y'aliey faults
tttttlts kite-yin
known to to exist
exist aa fewten miles
I'niles further
further to to the
the east thiliaekle ton.
east (Shackleton,
195l.m373t
1951, p. 373).

'f'i'i -}~".'1'.rln."
(c)_ I The Kapkitoi and 1't.-'_-'.-I' Associated Fritz-air-
.4.1.~'-.I.-".-"11'.-'1'1't‘ Faults
Smaller oblique to
Tait-its oblique
Smaller faults to the the main main Rift Rift Valley Valley fractures, lraetures. ean can be seen in
be seen the
in the
southern Cherangani
southern Cherangani hills. hills. TheyThey are probably braneh
are probably branch faults, faults, or or seeond
second orderorder shears.
shears,
l'orl-tingIr from
forking from thethe. sides
sides of
ol‘ the
the rift tilt in in aa north-westerly
north-westerly direction, dit'eetion. where '1'1 here cleavages,
e.e.'.1'1g .s. silicified
silieifietl
hre11tas. and
breccias, loet.l displ
and local ...entet ts indicate
displacements indieate their their position. position. The The trace
trace of ol one
one such
such fault can
fault can
be followed for
be followed miles to
seyetal miles
for several to thethe WNW. ‘01 NW. of of Chen'tut'ttikoi
Chemurokoi (plate (Plate III and another
"'ui and
[[1 (b)), another
is followed
is t‘ollt'iyy-etl by
by thethe Kapkitoi
Kapkitoi valley, valley. the the line
line of of dislocation
disloeation passing passing approsin'tately
approximately 11111 two
miles to
miles to the nt'II'th-east of
the north-east ol Karuna
Karuna and and following
tollt'issitg aa north- north-westerly yyesteryl direction
direetion tt'iysartls
towards the the
eonfittenee of
confluence ol' the htoiben and
the Moiben and Arobobutch
--'\r1'Ibt'.1b'uteh rivers. r.ye.s. The T he fault lault lets lets downtotyn phonolite
phonolite on on thethe
south-west against
south-west against quartzites
etuat'tzites and and para-gneisses
para-gneisses on on the the north-east,
north-east. and has an
and has an indicated
indieated
st'ILIth—yyestet‘ly throw
south-westerly thron of of about
about 700 TDD feet. feet.

[St LINEATIONS
(5) 1.1xei'1'ttotss

Lineations are to
Lineations are seen on
be seen
.11 be esposed surfaces
on exposed mueh of
oy'er much
surfaces over of the southern C'herangani
the southern Cherangani
hills.
hills. They are partieularly
they are well deyeloped
particularly yyell as an
developed as expression ot
an espr1sston quartz orientation
of quartz orientation inin the
the
massiy-e quartzi
massive tes ol
quartzites of Kapsilia.t and Chemurt'tkoi
Kapsiliat and Chemurokoi, andand else“ h re oeeu:
elsewhere occur as striatatns due
as striations to
due to
corrugation of
.orrugation of mieaeeous partings and
micaceous partings the intersection
to the
and to of eleayage
intersection ot and bedding
cleavage and bedding.

1n the
In yalley and
high valley
the high ridge eountry
and ridge country of the north-eastern
of the part of
north—eastern part the area
of the lineations
area lineations
generally
generally plunge gently to
plunge gently to the NINE. parallel
the NNE. the axes
to the
parallel to of minor
axes of folds. In
minor folds. the south—
In the south-
foothills of
yyestern foothills
western Kapseryya region,
the Kapserwa
of the parallel the
they parallel
hoyyeyer. they
region. however, thrust—front
the thrust-front
flanking the
flanking the hills, plunge gently
and plunge
hills. and gently to the SSE.
to the and south-east.
SSE. and south—east- TheThe latter lineation
latter lineation
trend is
trend is also parallel to
also parallel to the
the regional
regional strike of the
strike of the Turbo
Turbo grandiorite and migmatite
gran diorite and migmatite and
and
is maintained
is maintained over
over a a large
large area to the
area to the west
west and
and south-west
south-west ofof the
the Cherattgani hills.
Cherangani hills.
'11 here the
where asis of
the axis oli plunge
plunge isis always
alyyays gentle
gentle toto the
the north-west
north-west or
or south-east.
so ut h- east.

The commonest
The both in
lineations, both
eomn'tt'inest lineations, the Cherangani
in the hills and
Cherangani hills the Turbo
and the are.
regions are.
Turbo regions
therefore. parallel
therefore, to the
parallel to aaes of
the axes minor and
of minor majtn'tfolds
and major and are
folds and E lineations produced
are B-lineations produeed
by rotational
by movement during
rotational movement the regional
during the folding In
r'~r1mat folding. In the stones of
the zones tht'tIsL
tttat-tirnum thrust,
of maximum
hoyyeyer. aa less
however, less common
eon'tn'ton type
type ofof lineation
lineation isis seen
seen with
yyith axes
ases almost perpendieular to
almost perpendicular to
the regional
the B lineation: this
regional B-lineation; this has produeed by
been produced
has been dit'eet penetrative
by direct ntoyements
penetratiye movements
during thrusting and
during thrusting aeeompanied by
is accompanied
anti is by stretehing
stretching of reeks in
the rocks
of the in the direction of
the direction mots-.-
of move-
rnent. It
ment. It is
is evidently
evidently an an a— lineation producing
!X-lineation produeing rodding
I'odding and and mullions
It'Iullions perpendicular
perpendiettlar
to the
to strike of
the strike the mylonite
of the zones.
mylonite zones.

("ti") JOINTS
(6) ttt‘st-i'
'l'ension- or
Tension- or eross-jt'Iints
cross-joints are et'itttn'tonly deselt't'tetl
are commonly developed in in all
all rock
took types
types of the Basement
of the Basemem
is;_.-1ten't. but
System, but are
are most
m '_'.I.st obvious
obs-'itoes inin the
the quartzose
ottartzose para-gneisses
para—gneisses and and quartzites,
ottartzi tes. imparting
impart ing aa
marked eleayage
marked cleavage to to the the latter.
latter. In
to thethe Cherangani
Cherangani hills hills the
the dominant
dominant trend
bend of of these
these
jot nts is
joints is east- 11".: st. with
east-west, with deviations
deviations of of up
up to
to 150 15' onon either side of
either side this direction,
of this direction. soso
I. teht.prodttee
they produce aa regular1'1egtt lat splitting
splitting of the rocks
of the roeks almost
'.tln't1'Ist perpendicular
perpendiettlar to to their regional stt‘ike.
their regional strike.

.
 "" ---

3~

.— ‘.‘
LILJ
111 the
In 11111111411161;1'11'1'611. area
111.1' Turbo-Kipkarren [6111111111-1011‘111111: in
1'11'1'11 tension-jointing 111 the 111111511111: 6:'111.11=.11111116
1116 massive crystalline rocks 1111:1111
11 1111111111 a:1 north-east
follows 11111111—' 16116: to
1111 south-west
111'111111'1- '11. 13.111 trend
11'6111'1 across
1161611111 the
1116 regional
I1: 3111111111 strike,
111111116. and
1111111 in
111 conjunction
1'1‘111111111'11'1111
11.1111 steeply-dipping
with 1116611111'1IL'1'113111111'1.1111111616111111
strike-joints causes 6111111661116 1111111111111 of
the division 111'1'11111-11111111111'11 11111111611..-1 blocks.
outcrops into rectangular 611161111.
11.111166111111111 joints
Longitudinal j11i1115 following
‘1'1‘111111111'11111‘ the
1116 strike
1.1111116 are11:6 not
11611 so
1.1161 conspicuous
61111111616111.1111. :11: 61'11111'1-11111111'1 but
as cross-joints, 1.111:
:11'-.'.1.'1111'11'111111|11.'11611611111611
are commonly developed in 111 the
.1116 folded
1111:. 6.1.1 rocks
1'1'1'1111'. of
1'.- the
11'16 (1161:1111:
Cherangani 111:11 hills
11:111'1' 111'
as»; radially
1"1-11-11 '1-1111'. disposed
111 111:1111'1'1'
1'1'1'11'1L'11‘61'1 about
fractures 111111-11 the
1111': axes
1717111651 of 111 folds,
111111111. and
1.11111 as11.11 bedding-plane
1161'11111113-11111116 joints.
111111111.

5111161111611 in
2. Structures in the
t116 Phonolites
P1111111'111t'611'
Apart "1'1I'111‘1 late
-"-‘11|L"1'11'1'Lfrom "1'61'111'11'1. andlor
'.1'116 Tertiary P ‘1'-111-1-11‘1- faults
111111 111' Pleistocene 1111611611 to
1111111111: referred 1116111116.“.116
11:1 above, 311.11.11.1-
the phono-
111611 are
lites :116 devoid 1116111111 of 11111161111621... The
}1111:111-L‘1T11-'1:111'111111111111111 structures.
11111 post-consolidation gfi‘11111611'}.' of
1116 geometry 11111111111116 crystal
11f phonolite ..'.r'_1..1~:‘1'1'11l
161111116 was,
texture 11111611611: influenced
11111.11. 1.1.11 strongly
1.1.':1.~;- however, 1111311 6116611 by 13111111111116 at
11111. flowage
1111' flat 1116 1111116
:'-.1 the time of 111' 6.1111111116111-
extrusion, as 111-1 is 1.11
1111111111111 by
shown 1.1116111111116111 of
1111111112611 orientation
1111' a'11 marked 61111111111611 felspar
111 contained 1161111161 to
pl’lfli‘l.t1‘.1Cl':1:'~IIf'-1 parallel
’1'-111111111 phenocrysts 1116 base
161 the 1.1111111
111' 611
of
11"
each 611 flow,
11111.11; so 11.11. that
1111.11 in
111 vertical
1.'1:."1'.i1.'11.-. 1266111111171
I l'
sections 111' of 111.6
the lava 1111111 the1116 11161111111.
majority 1111111111": of the visible111111.16 felspars
1'61 111-11 11'11
are 111'11'1 111111111111 disposed
:11'6 horizontally 11111111111611 in in a'11 dark 111-1111 matrix 111111611 is
1111111111 which 15' sometimes 11111111'—.~'111'1."11111611.
11611161511165 flow-stratified.
Tl1611'11:111:—'11.11'.111
The orientation of 1111611116131 111' is
1'1J' phenocrysts 1161 so
E11: not 6:111:11; on
.1111 strong 111'11‘121-'11‘1‘.E'11 51111616611.
1111 horizontal surfaces, i.e. 1.111616
1.1.1. where
the 11111-1111.. are
1116 flows 1116111611 in
1116 viewed 11111111116111161111.1'1'
11111111.. and
1'11 plan, frequently they 1116.31'11111166111'
appear to 111 lie116 at 1111111111111. but
.11 random, 6111611111
'61:: careful
examination mug-111111 shows
1":11'111111'1111111111 usually '11-:1 11111111111111 of
1111111111. a:1 preponderance 11111131111111i1'51115- with
111' phenocrysts, 11.11611 11'-61111115116
111111.111 axes deviating about 6111111111
11161-111. indicating
a'11 mean, 1111661111111 of
1116 direction
11111161111116 the 11111.1.- These
1'11 flow. 11611115 (Fig.
'111'6‘1'2116‘. trends 11:16. 6) 1.1111111. the
1'11 show {11611-111
1111151111 Gishu
1116 Uasin
116111.111 have
flows 11111611611 towards
116116 travelled 11611111111111 the 1116 west 111'11‘111—11116111. Flow-orientation
:11111}north-west.
111161.11 and 111111-1'11'1'61111'1111111 of 1.11161111-
11f pheno-
1'1'11'1111‘1 is
crysts L'lL'H'tfiI‘fl‘IELl by
1111611 confirmed
1.11 often 1'11. the 611-1111211111:111 of
1.116 elongation 1.1'-_'1.‘11'vesicles
1.11__-'gas :11 the
1'-'.'-'.i'1,'".'1:'11 in 51611111" general
1.116 same 1151-3613111
661116111: direction.

\H—XH‘NERAI DEPOSITS
VII-MINERAL DEPOSITS
1-‘1111 assessment
An 111' the
11'-.1.1161111111111111 of 11111161111 prospects
1116. mineral 111' the
1111111116161 1'; of 111611 is
1116 area 6111116116111 by
LS. governed 1'1‘1111'1‘111161
1111' following
1'1}. the
.1
considerations:
1.11'11511116:-_'l11l1‘.'l_1."1 1 --
- '---'11:1-.'1--"':' -"

1. Lava 6111.615. approximately

1.:11'11 covers 1'1'16—1'16111' of
111111111111111:1161} one-half 111' the 1111: area11111611 and 11621166 reduces
11:11.1 hence 1'6'11131-‘1351 the 111.6 1111.111
total
11166 of
area 11111-11I211115111j1’ mineralized
111' potentially 1111111611 is
1'11611' which
1.1111161111111611 rock 1111111111116 for
11:. available 1111' surface 61.111115211111116: 111'
111111'1'1'166 examination; on.
1.111161' hand
11111: other
the 11.111111 fertile 1161"116d from
1'11'11'11; derived
111161111116 soils
1'61'1116 volcanic 1'1'1'111'1 plateau 1111.11.11 are
1.1111161111 lavas 111'6 of 11'.-1111111111166
11..F importance
311 11111
in an 66661111111111.
essentially EiLjI‘lCUllLEl‘l’il
agricultural 6111111161.
district, 11111.1 and tuffs 11111.1; and E11111 weathered
1.1611111111616111 gneisses
1:1-11.611.1.1.161. beneath
1.161161111111116 the
111111111 C'ElI'T'j:
lavas 611'1111111—1111'111161'11 which
carry ground-waters 11.111611 61111
can 116 :'61:'-'111'1"111:'1'.1 1111'
be reached 11116641111611 'and
by bore-holes 11111'11 1'also
111111 1:1.”1'6
give 12-516rise 111to
1111111111111
springs :11 at the11'“: 1111111311111.
margins 111' 1116 plateau,
of the 111111611111. 111'so. .'1 11"1.‘-1111"1-'
contributing 1-‘.1‘1711g 161to 111.1:
the 1.111' 61'1111 water-supply'
overall '-.1.:1'1-.1:'-~'11111111j1' 1311'
of
1.116 '1'1:'.1:1.
the area.
611611111611 and
131111161111 gneisses
132115.121‘1‘111‘3‘1‘1 System 111111111 in
:1.'h§.1~'11.'. found
'.'-11111 schists 111 the L 16111116111 hills
I1'11111161'1'1 Cherangani
1116 southern 1131.1.
1

2. Basement
611111111111 of
consist 116111 1116111111. rocks
111611111111111111111111 sedimentary
1' 1111111111111. metamorphosed
1'11' regionally 1.11111 no
‘1'1'1'111-‘111'111 with 1111 1:111'
granite '.1111'11151111-111 111111
31111112 intrusions and
16111 1'pegmatites,
few 11":'111111':111:;16'-11 5.1.1
so 11161
that 1111111
only 61:1"1111111'1116
economic minerals 111:1161'1-111'. produced
pI'L'I-11Ll1'1-‘1-‘11 by 1:1}. reconstitution
16161111111111.1661“. of' 1'11 the
1111'
1.611: 11. 611.111. such
11111111111111 sediments,
original :16 graphite,
1.111611 as 1‘131'1'1‘11121131'161'11 and
11111111111111-11111'611‘16 refractories,
6611111111161 alumino-silicate 111-11216:- are
111111 garnet, 11'-'6 1111611.
likely
:11 have
to 1.111116 developed.
11616111111611.

3. 11111561116111 System
_'1'. Basement 1'11'1"1~.'.I of
51.11116:61 rocks 1111': western
611' the 1111111 of
11161116111. part 11113 111611.
1111' the area, although 1“;
11111111111..- in
1111 11. 1. '11-11.111 granitic
. 1 1. _ . 1
1'1111‘11‘11-11111l111‘1. 1'.-E11116 1:11:61'1 6111111;'1_- 111 111-66171 1.1-1111111 1611611511111 [11'-1'11 11 61.111111111111113: '.'-11'1]. 1161111111.
4 . .1 1 -'.='_ 1- .
composition, have been eroded to deep crustal levels, so that a contrasting sedimentary
-
1131611 to
1'11‘1'132‘ likely
cover 1111UCT€11TT62L1 veins
6111111111111 mineralized
11'1 contain 1.1.1 not
1111-11111. is 111'61'161'11'1'1.
1161 preserved.
1116 1111111
4. The 1116111'11131'111'111111 11111161'111161-"11113111
only metalliferous mineralization recorded 1'661'11'61611 in
111 the
1111': 111.111.11.111
region 1.1.'6L:."1. 11'.: tension-
occurs in 1611.11: 111';
111111116111166 with
:1111111 associated
faults T61'11111'1; or
11116 Tertiary
11111111 late 1111 valley
P116 11 1.16 6116 rift
.1: Pleistocene 1'1'1'11'1112'1'311.
11611116}. fractures.

1. Gold
1. Gold
111 1933
In 11.1.13. gold 11111111 111116
lode 611111
and 6111111111
alluvial 611111111.
claims 111616 166113161611 in
were registered 111 1116 K113111111 1111.11
the Kaigat and 1511111111111:
Sosiani
1111161111 11.111.11'
valleys approximately 1'1711'111'11116111' 1611 11111611 11116111
ten miles west 1:11' Eld61'61 and
of Eldoret 111111 in111 1116 L11116 Nzoia
the Little 311-16111 valley
15111116111 61.111111
about
111311611
seven 11111135..
miles south-611111 south-east 61f 1'11112}-"1‘1 .111‘11111121
of Hoey's Bridge. Peggings 131161.1'1'111161: 11'61'6 1613311161611 1111
were registered on Plots[31111111 61113125.
Nos. 756. T511.
T111 'T_:1.
761/2,770/2,819, ._1 "1111.161111]
2971/R,R- 211TI 2971/3,3768 ‘1T1'i11'11 111161
and 4354, ‘35—'11 but 11111 1116 611111111111 were
the claims 11616 111111111611
allowed 111111111116
to lapse
in 111134
in 1934 1.11' :'[1‘11'1‘1'111 16611-111
without record 61' of 611111 p1‘131111L11‘111211‘1. Trenches
gold production. T1'6111'61'16f1 and and 111111116
shafts 1111111611
which 11611 had 116611
been 1111611611
opened
111 1116
in the 61611111.;
claims 1.1.6111 west 1:11'E1111'1161
of Eldoret were 1111'61'6 16116111611
reported 1.111 on by 111113111111'1'11-1-111561111611
Murray-Hughes 11113-11 (1933, p. 1:1. 18)
11.11 1111
as
11111161111111;1 small
containing 1111113111 11111511111:
quartz veins11'611'111: 1116611111111};
measuring up 1.111 to111 6111111
eight inches111611613 in 111 width
11111111111 1111111513,
lying in 111 1111111.-
horn-
hlEI‘ldE-EETHEI
blende-garnet 1111611111. gneiss 61111 and 1161111111.
schist 11111116111611
Although 1116 the veins 116111.111 were
111616 proved
1116111611 161 to be 1.11: g11ld-13131'1I‘1I‘lg
gold-bearing
111621
their 1.161111161161111
geological 5.6111116 setting 11111-1115
was 11131not 66111611161611
considered favourable favourable 11' -11 11113-111316
for payable gold gold 'values.
1.-"111116.11-

'-
 39

1311111111:
Quartz veins 1111:1111; can
can bebe Seen
seen in in 1'outcrops
111'11:1'1'.1]:1.11 11f_1_111111
of pink 11'1e1'e11'
or grey g1'1111111111'11'111'1'
granodioritic 11111111111111:
migmatite in 1'11
the
the 3111111111
Sosiani valley, 111111111;- 111111
and 1'in11 111:
the 51115111111111
Soysambu 11:1:111111 section 1111' of 111e.
the 1131:1311.
Nzoia 1'1111e111.
valley. T111111
They 1:111:111111'
seldom1'1
e111'ee11
exceed two 1:111-'11 feet
feet 111 in 111111111
width 111111
and 111'e
are 111111.111
often 111.111.11.111
visibly 11111113111111.
lenticular, 111111111111;
thinning out 11111 11.1
to 1.111111115111111
stringers
11111111111 1:a fe11.
within few 1111111111. 51.1111: of
yards. Some 111' thefie
these 11e1' veins 1111 111111111111
contain a11 1111111:
trace 1111' 1.111111 on
of gold 1111 11111111-_
assay, and1111111 it
11 11 is
111111111111: 11111.
possible that 1111111131.
others 1:111:11111'11
contain 11a 1'few 11'111' 1111111111.
dwts. 111' .5111111. 11111
of gold, but 111 1'11-111.1. 1'of
in view 11' 111e11'
their 111111111
small 111.111
size
1111111111111 is
erosion 1'11 'unlikely
111111'11e111' 111
to 1111111e
have 1:111-11.111111
brought 11111.1 111 111111
about 11111111'1e 111111111111
any notable .1-1111111'111111111'1 of
alluvial concentrations 111' gold
1111111-
~ 111 the
in the 1111111131111.
adjacent .11-1111111111111.
streams.
T111 {(1115111erite1
2. Tin (Cassiterite)
SEC-111111111111 of
Specimens 1111' 111'11:1111:11111'11e
granodiorite and 1. :111 amphibolite 111111111 1"1'11111
11:1111111'111111'112 taken from the 11111: Nzoia
1‘.-1e Little 111111111. 11.1111
31511-11111 valley and
11.111111111111111 11.1
submitted to 111-.1
the Mines 31131:: 11:11:] and (.1e111111.111i
Geological Department 1211:1111111111e11 11;. by P. 1". R. 111. J. .1. M.3111. Heard
HL111111 in 1211 19331‘11-'33
1 111.'
were e1'1'.' 1111111111
found to 111 1:1' :1'1E'.1.11'1 111111111
contain small 1.1-11111111
grains 111' of pale11111: green
11.11.11.111 1'cassiterite
::1111'111111'1111 111' or tin 11111111111:131.111.11'1111'
stone. Duplicate
111111111111
assays made 1111113: in 311 3111' 1111'1-1'11' 111111
Nairobi and 111. in- 111:'.11‘111111'11111'111:-'.1'1111'
the laboratories of 1111: the Tang-111.11:
Tanganyika 111 III-11.11111
Geological .1'..1'11:11'1 1‘Survey
11.11'11'1:'_-'
I
131::111'1_1"-.:11e'.11.
Department, 1'confirmed 1_'..1:.-1.'11.1:11 111111.
that 111' of 1‘six1-1:11 511e113111e1111
specimens 1111111111111111
submitted five 1'11-e 1.1.1.111.1.11
contained 11111111111111 amounts 1:11- of 1111tin
I
'3‘3‘1'1‘3‘3 (Sn02)
oxide ‘1"1'11'1121111 between
35133131.] varying 1.1.113 and
11:111-11'1:'er1 0.03 11.1111 per
111111 0.46 3:111 and
111'-11' cent 1151-1111 2.75
111111 a'11 sixth 2.7-3 per 1111.1' cent.1:11.111. Tin'1
111111111151
claims located 1111217111111 in 111 the1‘1: Little
L1111e'111.1111:1_"1'.1.1'1e_1'
Nzoia valley 17111 11111111. 4342
on Plots 1'13 12 111111
and 11"—1'841,1. and 111113 1112111.:
near the [11: Moiben3111111111111
1'111'1' 1111
river 13111.11 Nos.
on Plots 3111111. 1.1.1.3
853 111111
and 1'1-1"; 854 were 1:11:11: registered
1'e1.1.11111:1'e11 by 1111' 1:11:111'1'1
Heard in 1.11 April,
._1‘11111'11. 1933,
11.133. but 11:11 no
‘3‘3‘311‘33‘3' deposits
workable ‘11'1131‘1'15 were |i1111111 and
1111':'1:.' located .1111'11111 1111111'111'111'111'11
the claims were allowed11111111111111 to 111111.11 in
1-.'1 lapse 1'11-3111111151111;
111-11 following
111 the
11111:.
year.
{3'1'11111;111:1'1111—‘1‘1e111'1'11g
Cassiterite-bearing 11111111111111 gneisses were 1111:1111 11311.11 1'1-1:1:111'11e11 in
also recorded '111 the
1111: Nzoia
3141111111. 111111-11;
valley west 11111-1111 111' “1'11-'1.":
of Hoey's
Bridge by
Bridge 111-- Murray-Hughes
"1'1 111'1'111-'HL11_1111e.1'1 1"'1"‘.3.3.
(1933, p. 1.1.131.
8). The 1111'e1'111:1._11 1111
The average tin 11111111:
assay 111' 111111111111 11111111111111
of several samples was 11.1111
111.112.
0.02 per per 1:11.111
cent 111111
and Hughes1111111....11 11111111'
concluded . 11111111 1111111
that 1.1111111
small 11111111111111
amounts 11111111111111"'11'1'1'1'1'3
of tinstone were likely “‘59-‘11 11."
to be '1'-"17‘
11..'_11'e1_-. 111.111
widely 11111.11e11'111
distributed 1111.11111e111.
in this area.
The present
The _p1'e11e111 survey 111111-'e1.-' shows111111111111 that
111111 disseminated
1111 1111:111111.11e111.11.1'1.11.- '1er: 1e occurs
cassiterite 1.11:1-1'.1111 within
11111111111 11111111
and near 11:111' the 1111-:
1111111111 of
margins 111' a11 flow-foliated
flee—111111111111 xenolithic 11e11111it111'1: granodiorite
11.111111111111111: 1.11.11e1'11pp1'11'1
outcropping at 111 Soysambu
51:11.11.111111. '111 and111111 occupy-
1113311131"
1111.; much
ing 11.11.11.111 of1.11' the
the ground
1:111-1111111 to 11.1 the
1111': west
1:11:11 and111111 :11' 111111—1111'e1'11 111'
south-west of 1—111e111
Hoey's.11 Bridge; Briege; concentration
1:.e11ee11l1'1'1111-111. of 111'
1:11111111'1-11'11: in
cassiterite 1'11 111.:
the g1'11111.'1111111111:
granodiorite is 1'11 1111'
far 11111too low 1111111' 111 111111111111 111111111111.-
to warrant mining, but 11111 1111111111
grains 111' of 111111111111
aHuvial
111111111111: 1:11:1111'
tinstone occur in 111 heavy
her-1111111 concentrates
11111111111111.1111 from 11171111 111111
thin river 1'11-er sands
51111111 and 111111 gravels
3111111111 111:1:111'1'11111
occurring in 1'11 the1111'.-
L1'11Ie Nzoia
Little 1111111111. north111211111 of 111' Soysambu.
51111111111111111 There There are, are. however,
111_11.11'e11-'e1'_. non11 extensive
1:111e111'1111'e aHuvia'1
1111111111111 benches
1:111-11:11.11
either
either in 111 this
1111.11 11111111111111
tributary 111' or in 111 the
1111:. main
11111111 11-' 1-1111:1_1-' 1111
valley of 111ethe N15111:.
Nzoia further further to '111 1111:1111e111.
the west. A .111 1111.11'e
more
1111111111111111:
favourab~e 1:11:11 area 1'1-11"
for 1111111111111
alluvial dep11111'11'11:1
deposition -lies lie: in 111 the
the 1x11511111
Nzoia va']ley 11-'1'1111:-' 11ppre111111'1111e1111
approximately .111' six11 miles
11111e11
1:11:1111-'11.111re'11111111111111
downstream from He111111e1111
Hemstead's Bridge, 111111111. immediately
1111111111111111 -' 1111111111:
outside 11111 the western1111'1::111e1111l11'margin
1'1'111_.1_111 of 11'-'3 the
111e
311351.
area, 111-'11ere'
where for 111.11 11a 1111311111131:
distance 111' of 111:1
severa~1.1111 111111111
miles The- the Nzoia E11111 flows 1311111111 11111111111111
sluggish'ly in 11a broad 111111111 1.11113
and
51111111111111
swampy vaHey 111111111311 11111111.
floor.
.3. Iron
3. 111111 111111
and 31"1111131111e'1e
Manganese
S1eep111'—11111p111g sheared
Steeply-dipping 111111.111e11 and 111111 tineated
11ne111e11 quartzites
111-1111111111131 are '111'e veined
11-'ei111:1'.1 and 111111 impregnated
1111111'eg11111e11 with 11111111
1111111 11:-11111:.111
iron oxides in 111 the
1.111: 1111111111111.
Karuna 1111111 fault 111:1'11:
near 11111111111111.11-
Kibuswa. The 111111e1'111..11111111111 can
The mineralization 1.11111 be .1' 1ee11 1.111
seen on 1.11: the
111.'e.111err1 111'
western side1'1e of111' the
1111: Moiben
11111111he111'1'11'e1
river at 1111. the
1111: bridge
h1'11111e 'between
1111111111131 11(111111'
Kibuswa 11111'11 and1111111 Rap-11111111.
Kapsiliat, 1111'11e1'e where
111ei111'1 of
veins 111' reniform
11111111111111 grey-black
11.111111111111111; specuJlarite
11111::11111r11e 11111.1 and martite11111111111.- coat 1:1_1111 the the ,bedding
111-11111111111 planes
1111111111111 of 111' the 1111':
q11111111i1e11 111111
quartzites 1111111 1:131:11. the
and impregnate the :111:ep e111-111111'111111-111'p1i1111g. shatter-zone
steep eastward-dipping 11111-111e.1'—1:1.111e which 111'.-11:11 is 1'11 mineralized
11.1111e11111'Ie11
ever
over 11a width 11111111111 of111' 60E113} feet.
1'1-1.1.11.-
The
The ironi1'111-1 1.1-111111211
oxides 111111111111
contain .111 an 11pp1eei11111e 111'11111111'11111'1 111'
appreciable proportion of 1111111g1111e11e.
manganese, [11111111113111
probably 11.11 as
11111111111111: T111111
manganite, 0 11:13.11 1:11:
Mnz°)IzO 11.111111111111111: MnOz;
or pyrolusite, 111111): 'a11 representative
1'e111'e11e111111111-e. sample
11111111111: 111' the 111'e
of the ore 11111111111111
assayed
21.114
21.04 pe.
per eeni 11111111111111.1111 11131111111111
cent manganese. (Analyst: 1:11: J.
J. F111'1'1'1.
Furst, 'L1111.
Lab. 31151.1.
No. 21113111.]
27830.)
11. firepllite
4. Graphite .
{3111111111111
Graphite 1111111111111
schists 11111e1'
weree recorded
ree11r11e11 in 1'11 two
11111-11 'localities
1111:111111e11 in111 the
the 111111111e1111 [.'1'1e1'111'1g11111' hiNs.
southern Cherangani 11113.11.
'1'111'11
Thin he111-1beds 11E 1:111-1p1111e-bietite-g11rne1 11:11111111
of graphite-biotite-garnet schists 111.11e1'1-111
outcrop 111 at the 11e1'11'1 111"
the head of 1.a1 deep
deep vaHey 11111.11e11-1 1111111111
about
11111: ae 111111111
haU mile 11.11
to thethe east
east 1.11" 1.7111111111111111 summit,
of Garamoso 111111111111. 111111
and 11a pink-weathering
pi1111—11'e11111ering flaggy 11:-gar graphite
graphite
g11e11111
gneiss 111-"11.11
was 11111 1:111:11 1111
mapped on the Ser11he31-11111'11 ridge.
the Sembeywa ridge, 111.11: miles north-west
two miles 111111111-11111e111 111'
of: Kapsiliat.
Kepsihat.
Sample:
Samples 111 of both 1111111 11111111.:
tYipes 111 of 11:11:11
rock 1111'ere
were e111-1e1'11111e1111111111
experimentaUy treated treated 1'for
11-11' graphite
graphite ree1:11.e1'11-';
recovery;
11.11 11a result
as result it1'1 111-111.11
was found f1-1u1111 111111
that the the Sembeywa
Sen1be111'1111111 1111111111e
sample yielded
yielded 11a 1'111111111'11111e pereemege 111'
favourable percentage of
erue1b1e—grede
crucible-grade graphite, graphite. whilst 111111111111 111e
the 12311111111111.1111
Garamoso 1111111111:
sample yielded
yielded 1.1-111111
only 'a11 little
11111e graphite
3111111111111 of
111'
f ~ [1111.11 1111111113.:-
poor qua'lity.

--
 ... ~

40
40

gneiss at
The gneiss
The Scmheyss-‘a is
at Sembeywa felspathie and
is felspathic centaining 1arge
granelitie. cO'ntaining
and granulitic, flakes
clean flakes
large clean
O'f accempanied by
graphite accO'mpanied
et graphite by veryvery little mica. It
lit1!le mica. 1t etttcrnps
O'utcrO'psolO'se clese tn
to' the crest elf
the crest. leng
O'f aa lO'ng
ridge abO'ut
ridge Siltl yards
ahettt 800 in the
yards to' nest O'fthe
the west Charangai river,
hi the Charangai river. andand can he fO'llO'wedfO'r
can be nearly
telless'ed fer nearlly
mile in
aa mile nerth-nnrth-easterly directiO'n
in aa nO'rth-nO'rth-easterly Nes- 2232
l’iets NO's.
en PIO'ts
directien O'n 2232 and 3052. where
and 3052, ntean
the mean
where the
ef the gneiss
ss'idth O'fthe
width 1U feet,
is 10
gneiss is easterly dip
with easterly
feet. with et' 55
dip O'f55°.
it's creshed
A sample ei
crushed sample the gneiss
O'f the gneiss was treated in
has treated Knapp and
in aa Knapp and lilates fieatatien eel]
Bates flO'atatiO'n cell
Ltsing 1t] per cent sedinm silicate and pheseeresn’: "H” as
using 10 per cent sO'dium srlicate and phO'socresol "B" as ceH reagents. Screen analysis cell reagents. Screen analysis
the graphite:
et the
of graphite cO'ncentrate se predttced was
cencentrate SO'prO'duced carried ettr
was carried O'ut in Retap screen
iii aa RO'tap and
shaker. and
screen shaker,
assays were made en the ; tie mesh cencentrate. the --—t1t'}
assays were made O'nthe + 80 mesh cO'ncentrate, the - 80 mesh pO'rtiO'nbeing discarded.mesh pertien heing discarded.
The resttlts
The ss ere as
resu'lts were telless s : —
as fO'HO'ws:-
Asst‘iizsts
Sratttas ANALYSIS
SCREEN
Screen t'rffs'i'erl
H.515. (*Tyler)
fits-em B.S.S. t—t’r. gms.
Wt. ..
+' ”H
22 | -.-—-
“-‘iil
I?2.80
__It..-t.

__ ea - as
-22+25 i4.95t' t
— “a 44st
-25+44 7-“.- s“-
27.57
__44_fi
-44+60fl '17.50
I Tit}
_ et'i —_ Fit}
-60+80 12.20
1 3 '2 I: '1
* - eat
80 12.73
I: 7";

'l etal cO'ncentrate

TO'tail l1.“
eeneentrate 77.75

E‘s-"eight O'f
Weight nf -10 mesh O're
- 'l|__t mesh treated
t'ire treated l.2]'i-.} grns.
=‘- 1,219gms.
telal recO'very
'l'ltet'ertfit'e tO'tal
TherefO're t'li graphite
rectisery O'f per cent
t'iiy'h'l per
ct_ip_e".':r_-trt=_ie = 6.40
graphite cO'ncentrate cent
is eces'cry O'f
RecO'very +30 mesh
ef +80 graphite
mesh graphite = Fit} per
: 5.50 per cent cent
petcentag ash
issay percentage ash in tit} mesh
-; 80
..‘| + ceticenttate = 7.45
t.--.e_sh cO'ncentrate in: per pet cent cent.
'"T

Assay
Reecrrcry O'f
RecO'very graphite
et'tteielc-grarte graphite
et crucible-grade = it? per
: 3.17 per cent cent
.-«='Iitt't.'r_1.-'s.r: M.
Analyst: hi. S.
5- ‘s-"ig.
Vig.
In this
In small-scale e~periment
this small-scale the flake
esperinient the sire O'f
tlake size the sample
et the is satisfactO'ry
sample is the
tier the
satisfactery for
prednctinn O'f
productiO'n crncihle O'r
er" crucible lehricant grade
er lubricant graphite. and
grade graphite, the ash
and the yahte is
ash va'lue alsn within
is alsO' the
ss'ithin the
ter bO'th
specificatien fO'r
specificatiO'n yarietics.
cemmcrciai varieties.
heth cO'mmercial
5. Kyanite
5. 'liyttnite
triahle kyanite
Set't fria.ble
SO'ft ritttcrep en the
sehists O'utcrO'pO'n
kyanitc schists shneider O'f
seetl'icrn shO'ulder
the sO'uthern en the
{Ziaramesra O'nthe
et GaramO'sO',
eastern slO'pes
eastern nt tf'iehen ya
siepes O'fGeben ft—‘layete. and en
ya MayO'tO',and O'nthe ss'cstern side
the western lndiyidnai schist
cit lariget. Individuall
side O'fJariget. schist
layers are
layers tsgrss'een 5
are 'between 5 feet and 20
feet. and feet. thick
2t] feet and cO'ntain
thick" and appresirnately 20
centain apprO'ximately per cent
Ell} per cit
cent O'f
hyanite in ss'ell—de-eleped hhtdes sshich ettcn stand net
kyanite in well-develO'ped blades which O'ften stand O'ut frO'm the sO'fter biO'tite-rich trem the setter Hittite—rich
ttatrirs O'n
matrix en weathered -‘sccttmtJ-_atiens O'f
sttrt‘aees. AccumulatiO'ns
ss'eathered surfaces. hltte kyanite
glassy blue
ef glassy ss'ashed
crystals washed
i._'j.-'anite crystals
trem the
from the higher slepes are
higher slopes in be
are to' seen in
he seen geliies at
in gu1lies the eastern
at the itint ei Ciehcn ya
eastern fO'O'tO'fGeben files-"fitter
ya MayO'tO',
and aa few
and tens O'f
t'ess‘ tO'ns high—grade a1luvial
et high-grade ryanite is
ailtts'iat kyanite is readilly asaiiahie in
readily avai'lable lecaiity. Else—
this 100cality.Blse-
in this
where the. E-tj-.anite-L‘.-crtt'ing reeks are deeply ss'ea
where the kyanite-bearing rO'cks are deeply weathered and cO'uld prO'bably behet‘ed and cenld prehahly mined to'
he mined tn
shailesy depths with
shaMO'wdepths cemparatise ease.
ssith cO'mparative Hei her the
ease. Neither size ei
the sire O'fthe kyanite crystals
iie kyanite crystals nO'r their
ner their
prepertitnt in
prO'pO'rtiO'n reek is
the rO'ck
in the sttillcient. hO'wever,
is sufficient, te encettrage
hess'es'er. to' hard-reek mining.
encO'urage hard-rO'ck mining.
Garnet
ti. Garnet
6.
Garnet is
Garnet eemmen in the
is cO'mmO'nin metamerphdsed rocks
the metamorphO'sed therangi'ni series,
et the Cherangani
reeks O'fthe eecnrring
series. O'ccurring
in hietite schists,
in biO'tite calcareetis gneisses
schists. calcareO'u!; anrl ampWbO'lites,
gneisses and where it
amphihehtes. where it _is tennd as
is fO'und grains
small grains
as sma'll
seldem esceeding 5 mm. and making up enly a miner pertitiin
seldO'm exceeding 5 mm. and making up O'nly a minO'r pO'rtiO'n O'f the rO'cks. It has, ef the reeks. M has.
thereierc. nti
therefO're, ecennmie significance.
nO'ecO'nO'micsignificance.
Dark hrnss'n rO'cks
Dark 'brO'wn helew the
etitcrepning belO'w
reeks O'utcrO'pping cliffs east
the cliffs ChebO'rorua, and
O'f Chehnrerna.
east et and en the
O'n the
crest Semheysya. are,
nt Sembeywa,
crest. O'f highly garnetiferntts.
hess'es'er. highly
are. hO'wever, garnetiferO'us, cO'ntaining eyer 60
centaining O'ver Est) per ef
cent. O'f
per cent
granular garnet
granular garnet intergrO'wn quarter ~nd
ss'ith quartz
intergress-‘n with eccasienaily diepside; the
and O'ccasiO'naHydiO'pside; reeks are
the rO'cks thin
are thin
sheets er
sheets O'r lenticles ettelesed in
lenticles enclO'sed calcarentts gneisses
in calcareO'us and measure
gneisses and measure up tn 6
up to' feet in
6 feet width.
in width,
extending the strike
aleng the
extending alO'ng fer several
strike fO'r hundred feet
ses'era] hundred se that
feet SO' that the amettnt ef
the amO'unt O'favailaMe garnet
as'ailahle garnet
is censiderahle.
is cO'nsiderable.

-r
~.,.
... -

311
41

At K1111111111111. an
.511. Kokorowa, 1111 exceptionaHy 1111113111111 1111.11"
1_1111:111:1-1-"11'11ph1'1111111: outcrops
1:13:11: garnet-amphibolite
:111::p111111111 1511” coarse over an 1111 111::
area
of 1111111111 two
1111' a:bout 11:11::1 on
11111 acres 111: 'long
1:111 the 1111111" to
111111; spur 1111: east
111 the K:1111:1'1111-"Ih:
1'11' Kapserwa.
1'.:1-1111 of :11111111111:d1;11r11:111
The contained garnets
measure 111 2
1111 to
111:111'1111': up 1111:11:.1 in
2 inches diam-1:1:r. while
111 diameter, 111-111:. the soils .1and
1.1111111111111111: 11111111
1'11: surrounding hill 1111.111:11
"111 hiB slopes below '11-111111
1h: outcrop
the 1111111”:111' composed
1:11.113; gravdls
111111211311 carry :1111'1':]11'111'
111111121111 entirely
1:1'1111111'11:1"I a1most of marble-sized 111'-11:11:11.
fr111:1111:d garnets.
1111112.1l:-111':1:1:1.'i fractured

7. T1111:
7. Talc
1111:1111: 11131111111111:
Takose actindlite .1.1.:11i111111:1'-.1
schists were recorded 1':1:1:11'1l:11 '.11 at 111: 11.1.1111}1-11-1.1.-111.-11 1111.1
the north-western end 1311'of ."11'111111-11'1.'lh:
Ndalat. The
'1..1|'1: 2:: #1111111”:
impure 11111.: F111Fr11111:F_-. mixed 111111-11 with
111111 11111113111114:
amphibole 111111} r11:1_".=. in 1'11 '11:: -1”.'"11 111:1..i1L'1111 '11"
J talc is
1:1: 11:11:11.
be seen, but
and intimately
31111 1"”..11' 11'11:1' prospecting
further 1:11'1.'11:1'11:=.:1:'1'.1.' in
5:1 the
131: talcose
'11-111:1:-111_—'. 'layers
1'1-1111:1111 :1
and mica
1111.11 11.
of this area1..-".1 might
the few
11:19:: 'locate
outcrops to
111-.1111.- ]1.”' :11”1:”1”1 1:1"
'lenses of
pure talc.
8. Quartxia':
8. Quartzite
Q11111'11:i1:11 1'of
Quartzites Cherangani 1111111
southern {1"111:11111'1:111'11
the 1111111111:1'11
11" 1|1: lUlls are :11”: 1::1.11':111:i1
extremely pure 13.1111: 1'and 1'111 1111:1111-
of 1.'considerable
111‘1d1‘:1
11111:1111:1”1'1 in
thickness 1'11 the 11111111111111 and
1."11:11'1111'1.:1J11”11. Kapsiliat
111:. Chemurokoi, '111'1111111111 areas.
11111.1 Kamna coarse andd 1'highly
'1111: 1:11111'1'11':111
1111:1113. The .-1'111:1'111 1.' .1'1-'111:_-1i-
crystal-
I111: -beds
line '1'-1:111 :11: 1111111111 free
are usua'lly 11:: from micaceous 1'11
11111111 1111-1211::11'111'1 :1'1-‘11'1F'11111: 11:11:11
or graphitic fOlia and and 111': -. 111‘-1111111. 1'on
often 1-ash-white
are 1':-11:11 11".-
:.'11'.:1‘11:1] 111111111::1.:11111'
externa.'l surfaces and translucent internally. The 11:1111:1”11”1:1”111
1'111'1111111.-.'T.:111:1'1111.1”I111”: proportion 1'of contained 11'iron
11 1:111:7111111'11 1'211'1 211.111:'11:-:'1:1.i
in selected
11111121111151
outcrops is 1111M: 111
111 'liable to 1'be 11: 11111112113111}
sufficiently low to permit 1'1”]1'11
1-1111 11'1rd11:1'1'1.-11 their use 11:1: 1111 source 11f
as 1'a1 111111113: of '11I1C11 silica in 111 1F11:
the
1'.:111'1111.'_”11'.”:1'_1::
manufacture 111 of 1.7111111
glass and 11.1111 refractories.
1:1:111:'11'1:1:1'.

9. Limestone
I.il11::1111111:

Severall 11111111111111 tons

'11-11:11:11 thousand 11.11111 of 11:11111'1: suitable
1'11" limestone 1:111:11'111'1: for
1'111' calcining
11111:-. 1'11'1F1: for .-.;'_.'."11: .'.11'11'1'11 111'
1'111' 'agricultural 111.111.13.211:
or building
51:11: is
lime 11 11111111111111:
availa:ble 111 in 1'1: ”111.11'F'1::1 valley.
the Moiben 1:11:11: '11::
The magnesia 11:11:11.1'151'1 1:1.”11111:111
content 111' of 1111.:the 1-1'1.1.'1.=1]ii:11:
crystal'line lime- !i11'.1:-
1111..”1111'
stones11 111:1};may 1'not 1-1'11 1.11:. 1111111111111: low
be uniform'ly l11'1'1' 1:111:111311
enough 111 1:11:1'1'11:1 their
to permit 1.21:1'r use
1.111: in111 111: the 111-11111131111111:
manufacture 1'of 1-f
11:11:11111'1: cement.
standard 1:1:1111'.“1.‘. Some
511111: of 1'11 11”.:
the 1.1111121111311
outcrops are :1: pink 11:11.“ in 311 121111.111:
colour 171111;".1
and 11'111‘11-
dappled1.- -1"1‘ 311111.111: with
or 'banded 11.111”;
.2 .. '.-..1. . .' . .... .1 _.
green 111.111.1'1.11'11-:1.1
'1:-1111 minerals, so they may 11.115.11111.11-.1111F1i]1'1".1111:1111.11'.-..1
have possibilities as ornamental 12111111111111.
stone.
-
-
10.1.11'1151151 1111:”! Road-Stone
Ballast and 5131111111-51111':
[5111":11'1F1111' lava,
Phonolitic 1.1.111. although
11iT.111"-'.i'.-.fi1 not
:1111 ideal
11::11': materia'l
:”:1:1‘1.:'.1'i;"1': for
'11:”11' use
1:111”: 11'
as1” road-metal
1'1”'.11”:1".-:'1'11::'_-.F or1.'-:' 'ba'1last,
1':-111.1111 is11. so
1.1.”1
.1:.11:'.11'..|11i'11 in
abundant 1111: Uasin
In the {21111111 that
111:111'. Gishu :i is
1.11111 it extensively. 'l'l11':
1111-11 '.'."1:.'1:'1111i11'.-Fj1”.
11'. used 11111'11'111‘1i11: is
The phonolite quarried 11'1'1111
I11 11111111'1'1:1”1 from
1.11 western
1:...
the 11.11.111.211 'plateau
.. . _--..
11..'5'.1:'.'111 escarpments
:111:11: 111.11.11.11 three 111...:11.11111r11.-1..1--....-.1
111-'4----I-'1-1_' ---I-_-
miles north-west of .-I 5-.
1.11 Bldoret,
1-._'1.
I 111111..11.111.111.111!
..1' .-. '.--_: .--1
and also at Matunda .-
."1I111.11'1d.-:
.- 1- 1"'I--'F

:12"
hill.
..'... . 1.-. ...1. .1.... . 1 1
11111111 from
Apart 11111.1111: the 11.11.11]
'locall 1111111111111
demand 11.-r . road
for .. r. 1. .1.
1111-111:1111.11111111111
foundation .'
material -. ' l '1
11.-1111:1111: 1.- . . :...'_ '. .
1.11111:
in the 111111111. of
vicinity L7'1:
111 Eldoret 1-...
1..-111:1
”.11-.1 Kitale,
and 1':-11111:'11"'.'I1”-.”'1'111- for
1111111111.: requirements 11”"11'11.111'.-g1 earth
1111: existing
1;.1'1':-1-.':'1j:'. the
1111' surfacing 1:1-"11'1'1'. roads 1':: the
1'1'11'11'111' of 1:1: plateau i:::'_'-_.T:.'_1
111': largely
11=1:'1.':1'1”11 are
1'.'211 from
met '1'1'1111": murram
111111111111 pits 115.111 excavated
1:11:11'-1'111.:-11 in
1':'1 superficial
11111113111311] earthy 1:1111'1'11' lateritic
1:111:11111: ironstone
1111111111111: 1.'-:1111111'111
deposits which 1111;11:1'"
111': common
are :111111'1'11'11'1 on1'111 the
111: lava 111111 111.11'1'1111':
surface.
i1. Building-Stone
11. Building-511.1111:
1111.1:11
Rock 11111111111:
suitable 1111' for 111111.1'
quarrying1'11--11'11.-”1 111111
and 1111:1111111:
dressiftg 1'into 1'1111 building-blocks
111111111111.1-111111:k:1' 1'is11 1111":
rare 1'in
11 1111.-
the 1111-11.
area.
E11111 11111111111111: 11:11.1
Both phonolite and 1111:1111
gneiss 11111':'.
have been ::11 '1'11:d
used 11.as11 bui'lding-stone
111.11]1:'111.11-1.111111: in
1'11 the
111: past,
11111: 11111
but 11:11: 1"1.111”1'11:1'
the former
111 1'111':111:i11'
is 1"151'131':'11i1 111
extremely difficuilt to 1111:1111
dress 1.1111 and 111: 11111:1 is
the 'latter :11. -likely
3:111:11. 11:
to be 1.11- fissile
11:11:11: 111111
and 1'varia'ble
1111. 1:1
in
C1:1111:111111111.111.
composition.
I'h: survey
The .11'..11"-1'1.':'_1' of 1'11' the
1"11': 1111:11 11:1111111-1111'111'1111' that
area demonstrates 11.111 in :11 places
11'.'.11:1':11 the1'11: phonolites
DF'11111‘11'1111:.1'1 1:11
of the 111: Uasin
I_'111'1111
1'11:
Gishu 11111 1111: 11111.11:1'1111'11 -by
are underlain 1.11” 1111'
tuffs 1'11 11111111-311'
and grits 111 ':111r1”'11:111'111'11'1:'111-'
some of which are:Li111;'11-'11:11‘111:11'i1'.i1:.1.1111111111111115“:-
'likely to provide good building-
11111.1:r1'111. Th1:
materiaL The beds 111-111.1 1111”.-are 1'111111111111 1.11111111111111111'1' soft
thin and comparatively '11:.11'1'11'11111'1111111111:111'111”1'_1'1'1}11”11.j1'11
so that they are nearly always 1111111111111- masked
1'by
11” 1:111:1'
talus 111:11shed 1'1'1'1111 from :'I'.-1: the F11' hard 11'11 1overlying
'. '1:-H1111; phonolite; pF11'111'1i:11'.-: because
1'::11..111.: 1.'of 11' 11'311
this 111:1' they 11:1:
were 1:1:1'1'1'
on'ly 11:11:11
seen
111 111111:11'1p11'
in outcrops 11::11' near Moiben 51111111111 ”111111 and HL'FE}
Sdby J'11i111. Falls. E11:11F1:-1'1”:.
Elsewhere 'loose 1".1111”: blocks
1111.11'k. of111.111 tuff 11:11:11
mixed 1111}: with
p1”11”1111'
phonolite 1F1"11”: 1111:111'
near 1'the 111”: Basement
13:11:111c11'1 System-phonolite
31'1lcr'1-ph11111111'1: :11111111”:t contact indicate 1111;111:111: 1111-1112: 11:11:11 11111;
these 'beds may be 3.1:
:1111:11.11'1'1-1:.
extensive, 111111 and it 1'1 is :1'1 1:11:111'111'.:1'1:1i
considered that '1'11111 111111111:1:1'111g
prospecting ::-.'111111111111'1:d
accompanied by -':'1_1' 111111111111"
shallow 11:11:11:pitting 111 at
11:':-':11.-1i
selected 11111-11 sites 11:111" near 1111". 11:11.11: 111' 1111: 11311111111111":
phonolite 111111111": 1':'1':1'-11 f111111:1- ‘11::111111::1 where
11'h:1"11'
,.I 11111211111111-1111111: is
building-stone
the 'base
1':”1' 11111111111111:
available. T111”:
of the
The .sinuous
11"..- 111111'1111 111111111:
margin 1.11
would reveal
of 11h:
further 10cailities
11111111113111: 119.11
the phonolite has 11a length
1111111111 131-1111113111
of about
13"? 1:111:11
135 mi'les in in 111: the 111:11 area 1."-”1' (see11: 1:11111L1r:11
coloured geologica:l g:11111g1:111 1111111
map 111 at 1.'-11d}.
end), :11 so 111111
that 1:11: the 1:1.11' 1’11111'1 :111:I1d:1
contact extends
111111111111
through 1'a1 11111.7: large 111111111:r number 111' of 1111111
farm 11111115.. plots. .[1 It (”11:11:11
does 111.11
not 111111111.
follow, 11111131111.
however, 1111-11 that 1111111
tuffs 131‘or grit:
grits
1111d:ri1': 111':
underlie the 111::
edge 1'of11' 11111: 11111111111111: 1:11':r;1-'11'}11:r:.:11:11::
the phondlite everywhere, since these 1''1' 111': 111-11111 1111:1111 111':
basal rocks are 1111:111
likdly 11:1 F1111:
to have
L
:1:1:1111111[:11:d in
accumulated in broad
11111111111 pockets.
p1'11:F-1:1:1.

l
 4:
42

Horizontal -blue
Horizonta[ blue tuffs about 200
outcropping about
tut't's outcropping feet below
1151'} feet the crest
helosy the the escarpment
of the
crest oi escarpment
north of Tx-toiben. e111 Plots {1351:1164 andL ““150. are
north of Moiben, on 'Plots 6837, 3764 and 850, are approximat~ly 10 feet approximately Itl thick and
feet thick and
would require selective
would require along the
quarrying along
selectiye. quarrying strike to
the strike to as'oid removal or'
avoid remoyal of _pr'ohibitise
prohi'bitive
amounts of
amounts of <lava overburden. This
las'a overburden. is also
This is applicable to
also applicaible the outcrops
to the in the
outcrops in Sosiani y'alley.
the Sosiani vaHey,
on Plot
on T1'o. 771.
Plot No. each of
[11 each
'FTI. In these localities
of these the tufts
localities the. are yirtually
tuffs are virtually unstratified and should
unstratil'ied and should
L'LitELtttaily'11-el'1
cut equaHy well in all directions.
in all directions.
12. Water
12. Water
The principal rivers
The principal riyers flowing through the
tlo11.inL'1 through the area in the
rise in
area. rise the. high t'orested couritry
high forested country
bordering the
bordering the. rift 1.-'aliey at
rift va!Ney ll11e1LL1 where
at Elgeyo 1.1.her'e the drainage of
the drainage or' thethe smaller tributaries is
smaller tributaries i1
controlled by
controHed by the the. absorbent
absorbent forest torest soils. soils. The The upper 1'11'er is
T1'1toia river
upper Nzoia fed by
is fed by thethe T11toiben.
Moiben,
Arobobutch, fL't111r1-1ng11i. and
.1Lr'ol11o'L1uteh. Charangai l_1.'.1.1'.1rtta str'L-11111s
anti Losurua streams and bec11111es aa sizeable
arid becomes ris'er at
sizeahte river Macy's
at Hoey's
Bridge. The south and centra!l parts of the area are drained by the Sosiani, Sergoit 11.1111
Bridge. the south and certtral parts or the area. are drained '11-y the Sosiani. Sergoit and
Kipkarren riyers. Ij-loret
Kiplt'arren rivers. Bldoret obtains obtains aa municipa1 munieiyal water-supply 11'11ter-supply from tributary ot'
from aa tributary of thethe
Sosiani. the
Sosiani, l'iilegirim river,
the Ellegirini rising in
ri1. er. rising in thethe Kaptagat forest to
l~L11pt11g11t forest the south
to the 1111' the
sou th of area; 1.1.hiie
tl-1L- area: while
pumps water
Ritale pumps
Kita[e 11.11ter from from the ltobhus river,
the Itobbus tributary of
r'i'-.e1.'. a11 tributary of the
the Nzoia, rising 11.11
T1'zoia. r11i11g \to'Ltnt
on Mount
L'lgon. How
Blgon. statistics for
Floss statistics t'1'_1r‘l.1'..olttc
some of ot the the riversrisers. in area from
the area
in the from the the records of the
r'ec1.1rtls 1111' the
'11....cti1 11.1. Ministry
ilytiroiL.1g1' Section,
Hydrology ot' Works,
.‘1‘1'1: 11. st1' ' of are given
T11. '."11. 4111 are
\‘1-"t1r'l.1s. Nairobi, l1el1111'1-
giyer. below:-
T.1.i1.i1 IV-ANNUAL
TABLE l‘y' -."1.1.1-L1_ .-Lt_ FLOW
'1-'r_1.':1'.'1.' OF
1111' RIVERS
ltrs't-‘rts IN
1.1 THE
1111. ELDORET
!'_'1_111"11.'1.1_1' AREA
111.1111.
Mean
.1'H'L''.L't.” Flow in.11 t"-.’1‘.'1't"t".1"'
1":1"'1-~'.' 1"..' cusecs*

T111111 1. R.
NZOIA lit. lr'tj11'115111s R.
ITOBBUS R. 5311.111
SOSIANI R.
R. '11: 11.-111.111 R.
SERGOIT Ft.

‘1'L-111'
Year T'r'.1'-L'1e miles
Three mil-es '."1=.1'.-.1'
Near At .‘iL'1.L'-11. miles
Seven 11.1.iiL's
upstream11111111
upstream from 1.111.111. 11.-L1 s
Glanville's 1'.'LiL'-1'e‘1
Eldoret [1.1.11
E. of
ll. .2 '1 Bridge
Hoey's Budge HLrlL
Halt l'ltiore'.
Eldoret
j I

Iii-4",}
1949 .. .... 79.17
71'7 55.12
31'2 513' '1'1‘
59,9 H157
11.57
111151;}
1950 ... . ... . 11111-1
106'4 111111-11
66,0 _1] -f.
31.5 1..].1.
6'14
l95l
1951 .... .. '155'1
133-1 4'; L'.'!
41.0 l5tl-5
150.5 I 521i.“-
32.9
l1-J52
1952 ... . ... . 21211.15
100,5 54-.5
34,3 .434
143.4 5'5
35'7'1
[9.1531
1953 ... ..
.. 11111-11
66'6 5t'i'i
30.1 ‘1‘-'4
20'9 I
i-l
4.1
I 11'11.
l954
1954 ... .. iii-Z
91.2 5415
54,5 _T 5
72,5 16.8
l955
1955 .. .. .1115.
86.5 445.13
46'3 411i
46'1 I ltl-l
10.1
*cusec-volume L'1i water
'i‘etlsee -—1.'L_1luri'1c of a go.
pusstrtg a
1.1.1'1tci' passing :11 point
given '.11 eut11e
measured in
11111117. measured cubic feet per s-L"L'-1'111.'L'i.
teet per second.
arms 1'1Ll_11'1-L"ent
Farms adjacent to '-.._1 the _111'ge1' rivers
the larger 1'11 e:‘- 1111L1
and tributaries
tributaries L1l111'1111
obtain that their water11 are: 'by11-1.' 111111.
ram,
1-111Lt those
and -
those not '
out so
-
so t1.1....11111-L:_1.
- ' - ""1
fortunately situated-"--1
1.tL.11tLL-. from
" ':
trot-.1 l.‘.11.1tL..1L-1.
'-""1-" '1
boreholes, L.11L.“1
'I- "1-
LiL-r..1.1. 11.1L.
--1-11'
earth dams, -..-'
.-1L1. -L.-.'1LhrttL1111.
'1".
and roof i'f'l. -
catchments. 1-1-: 1-
H.
:— .1. -1. - 3.-

Ftlrt‘L'i'Lt'L are
Furrows are used usctl to to d1111.1.'1.1.-'1'1.tcr
draw water from- l'rom- the the steepet‘
steeper '.t'atct courses in
watercourses in the.
the south-L11“.-
southern
t.'_'her'at1gttni
Cherangani hitis hills forFor both both 11'11g11111rr
irrigation and and the the generation
generation t_11,'-t1n1cst:-'-1L'
of domestic crc'Lt"i-L':1'-.,
electricity. During lilur 111g
recent years
recent years the the most
11111.11 sLtL'L1'e1Lstttl
successful method1‘1'1et'r1L1Li L1t' 1eater L'L1r'.-.1'e:"11'1tit1r1
of water conservation hasl1'c1. has been 11ehic1eti
achieved
hy the
by the eonstt'tictit'm
construction 111' home:11111. small
of numerous small dams. dams which which ct'1".lee1.
collect the the seasonal
seasonal run-oil run-off from t'1'L'1m
minor on the.
5ti':‘!.":l'l"..11 1.2111
r'11ittt1r streams flanks oi
the iLL'Lr'1lL1'. of thethe hills. On the
l1il'..1. (_iln the elevated Gishu plateau.
Uasin 115411.11
c.c'.'.1.teti Lia-411 plateau,
however, 111ailable
hoa'eyer. available surface surface other water is. limited: the
is limited; the L1e11.L1-.-Lli1.t't1=1r country isis crossed
generally flat L111.=.r11.1r1. crossed
by
by et1r11paratiyciy
comparatively few t'c.1.1.-' strcatt'ts
streams :ed recei'te less
and receive iess raitiiall
rainfall thanthan the the 1111 hghoouring areas
neighbouring areas
to the
to the west'.11'e1t and north l"'1't'"1""
and north (see p. p. El.
2), inin suchsuch circumstances ground-water obtainable
cir-eurnstsnees grt1uritl-1.1.1.te1' obtainablle by by
ht'11L1t-1L1les assumes
bore-holes assumes some some import:-11ce.
importance.
--'*~.1'ailable records
Available records of of some
some eighty-1i1; 1.1.11tcr- borirtgs made
eighty-six water-borings made in in the Elder et area
the Eldoret area
are
are summarized
summarized in in Tabie Table ‘1"_ V. TheThe bore—holes
bore-holes 1'ranging 111 grrig between
between 123 128 and and 5t11;_11"'teet
500 feet 9:1 in
depth, are
tiepth. distributed oyer
are distributed over the whole area
the whole area [Fig (Fig. tit; those sited
8); those sited in in .the rocks of
the rocks of 1hcthe
liascmcht System
Basement System generally generally obtain obtain water water from from the the upper pervious and
upper per1.-'it1us and decomposed
decomposed
1.1one
zone in in aa relatively_ impervious imperyious crystallinec1'1.'s.talline t'oundatiorr.
foundation, 1.1.'hilst
whilst bore—holes
bore-holes sited sited in in the the
phonolite draty
phonolite draw 1.1.'ater
water from from both both thethe upperupper'dceomposed
decomposed levels le1'els ot' the la1a
of the lava 11ndand tteeper
deeper
portions of
basal portions
basal separate flows
of separate flows where intercalated tui'l's
1.1.l1.c1' e. intercalated tuffs or volcanic ash
or 1.-'olcanic ash provide
provide
aquifers.
aquifers. Some Some of of thethe dc drillings reaLh
epcr drillinas
deeper reach throughthrough the phonolites to
the phonolites to thethe metamorphic
metamorphic
rocks beneath.
rocks beneath, and and obtain obtain their their mainmain supply supply from from this this leyel.
level.

-
 4.1
43

Collation 1:11"
(111111111111 L111':1'1'1-:—111_11111 111111
of bore-hole 11:11:11.1 indicates
rest levels that 1111.11:
111111111111111 111111. movement 1111:11'. of"1*" 11111111111 11:11-11:11 in
ground-water
11. |. 11'.
the phonolites 11
1111' 11111111011111 11111111111111: 11'11'1'11'
is westwards away 110111 from 1111: shoulder 111'
high 1111111111111
the 1111111 Elgeyo 1:51-1:111'1111111111
the E11'ge1'11
of 111: escarpment
and1111 11111111
down the 111'111'11111i1: gradient
1111': hydraulic 111111111111 the
11111111111: towards '-".'1:'11~:1 1:11"
1111111111areas
11111 lower of the 111111111111 near
111-: plateau 111111'Zi11'11.
Ziwa,
.E1'111' and
Soy 11111111: water
L1=111:11.1. where
111111 'Leseru, 11'1111:r often from the
11111111 from
11111111 issues 111-111: of
[1111 Ibase 111' the 11111111111111: in
1111: phonolite 1:311:111'1
1:1 scattered
11111111151
springs 11111111111:
situated.11 111 at 1111::the heads 1111111111 1111' ”11111111311 incised
of valleys 1111;511:111 into 11111.1 the 1111': 11.11.13.135
edges of 111.~ the
1111’: phonolite
11111‘11111Ei11:
escarpment. The 1151111111111
1:11:1'11'11111111111'1111: Karuna 1111111 lies athwart 111
fault 151111111'111111'1 this.1. 111111 1.1111 1111 111'
direction of 1111111111111
movement "111 .1'so that 11'111111'
1'1 111111 water
is 111111111 to
1'1 forced surface 111.
the 111111111:
1.11 1111 several 13111111111
at 11:1:1'u1 springs located on 1111—:
11'11:.'111:11 1111 line 111'
the 11111: fault (Fig.
the 1111121
of 1111: (Fig. 71. 7).
1111: Moiben
The 11111. lying
111111111111 fault, 1111111 to 11.1 the 11'-:11: 1.11.
1 111: west of the K111111131 metamorphic
11:1: Karuna 1.111111. has
F1'“'11T']"1‘11"1"1.‘13 strip, has the 11111
I 111“"111111:
opposite 6111:1111 111'.- groundwaters, p::1‘1111‘.ing them
1::'111J:11_111E111::'.1'. permitting 111::11 to 5111111 to
111 sink 11111111 levels
111 lower 11:111111 111111 11:311-111.
:
effect on and escape
northwards 1111111111111
11111'11111-111'1111 towards 1111: Moiben 11'-111:1.
the 11111111111 valley, 1111 1111111111 by
as shown 131' 1111:. 1111111: to
the failure 1.11 11:11:11
reach water 11'5111:1'111
at
4501.'" 11.
~15 feet bore-hole C. 1131:1111
in b111'1:—111'.1111{'_'.
1'11 111 1658 5111.111
sited near to 1111-:
1111: 11:1 fault-zone 111111111
the 111111111111: about 31211.1 800 yards 1111111 111'
111111111 north of

SCALE 0630' N
10 IS MilES
~

D . C25<0 Bore-holes ",itn

Hwtl". number
F1i_,""' :fi"
.__.1-

1 Frlr'rllh-I 1'1": I C :54: BI: E '1':-

Phonolites
0'-= SS Epr'ngs
Springs
Basement 51511-111: , D1551 -:r- :1 14111111111111.3113:11113113111131
/" Direction of ground-",ater movement
m.Basement System ;,C1"! [fr-211111;?"
(ma.imum 1111:1111!
hydraulic 1:15:13":gradient
EE'EIlatE-E.‘ from
estimated 11:1:1'1'1 rest
feat-1E"? 5'
-levels)
/ "11:111.: 11111111111111:-
'
“11' {”3" ' boundaries '-* . ‘1‘“1.311191311111111: ' 11-1 sections
121112111
“11

Geological /'.. Bore-hole line of

X :31.
X'

Far bare-11:11::
.For sections 111111-
bore-hole 51::1ic115 see .Figs. E and 99
F1g1. Sa.nd
Fig. 111E bore-holes
'T—aatinn of
Fig. 7-Location and springs
burn-11111115 and in the
springs in 1111111.
Eldnrei area.
the Eldoret

..
 45
45

1151110111151."
-r_ Tr'r']

1.1"..111.11111411:..11"1'-'.1'
(b) Bore-holes Sited 1'11. Phonolite-{Contd.)
51111-11 in

Eflre-
Bore- Depth
Depth 1:1
Depth at
' Depth Height 111
Height to Field in
Yield 111.
111:1Ie
hole L1..1L'L1111'111 and
Location 1111.? Plot
1131.11 No.
7111. 1:1 feet
in 11:1:1 1111'. 11:11
which 111111;}:
which 1.411.111.
I
gals.
71111.1.
No. 1.1-11er
water 11111-1131
water per
per day 1' . -.13.
'1111-.'-':11r-'L11':1-L
was struck .'1.-11:51
rises
I 1 1'1-'11.: .1
(feet) 1' 1'1-111.1
(feet)
11'
LL111-127
C.1827 Fer-11 miles
Four n11iL..~' SE. SL1.1:.11'."-11.-1'~'
of Nel's Bridge, B-iL'.-_L1L:. 888/5 1'1-1.1.1; ."1 .. 1511
150 41.11: 141-1
40; 140 1515 3-1-1111
34,560
-4 C.1846
1." .1521—111'1 F1113 miles
Five 1.1_: 113:1 NE. 711.1". of 1'.':1'11."e1. 8409
e11 Eldoret, '4|"'|‘..1 ... . ... . 425
5-22.11 11'11'71' 425
100; ~12; 35
.71."- ‘1'-11111:-
9,600
C.1870 .11171} 51.1; 1111 1'11
Six miles ENE. of Eldoret, 898 1:71'E. 1.11'1:'1:'-11.-1 L'.1 11":1-11 . . 350
35-11 241
2-1 60
1111'.) 411111111
40,800
('." .1904
*C.1904 Three miles
Three 1111. .‘11. WNW. 711191-- of Sergoit F31L1'111111 rock, 1""111;'1.' 886/2 1111111 2 111.11":
400 .1'1 : 380
51; 71.1-1'1'. '21 41'}
40 11:11:31:
10,080
"'('.1'.111'.I:'1
*C.1905 '1'11reL' miles
Three :1111L'..- N. 711'. of 11111111. 111. 861/4
1:1'[ Karuna, 1:11:11 —'1 .. .. ... . 21.11.11
200 1—'-i'1-
148 3.7-1}
120 1111711111
10,000
C2111???
C.1958 Three miles
Three 1111.131 NE. '."111'.(L'?|1'
of Nel's7111:1'1} Bridge, 1'1? 1L'11:1.e. 879/1 1171.1 1 .. .. "1'31
70 5'11
50 211
26 12.1.1111:-
12,000
I'.".1'?-'.:':L.1
C.1959 Four miles NE. of Nel's Bridge, 879/1 ..
1-'L1L'.r 1:1:Ie.;_. 7-1;. 1711121' .1 »: 111.11.1L1'L- .'.-'11 1 5-1.1
50 2 I
20 8.'.1' 11.-"4.111-
9,600
C.1'~1"1:-1‘1
C.1961 0111;-
One mile 1'1'111131' . . of".7‘~'~."1;-1'
E. Nel's1.. Bridge, 1}31'.1'._1__-.1: 781/3 .111. .71 .. 1]:
II2 98 111 2"
27 2.51.1111
2,880
11'. 1".1'1'12
C.1962 C1111:
One 111111.: mile S'fi'. SW. 1'11"“:1'L'1'11
of Nel's Bridge, Br1L11_-1L'. 1141111'311 8406/4 .. 124
124 ‘1_
87 :5
25 3.1211
3,120
[HIE-1131.1
C.1963 S11. miles
Six mile-'.1 NE. 7111'. 1:'of 111 """'"
Nel's:1 Bridge, [51111.13- 8383 11'..11'-.'1 .. :"-'.1
83 ‘I
51 17' 14-51-1111
14,400
('.'21'132
C.2022 "L11']1.' e miles
Three F‘.‘:Z1-1"-":- N. 7111. of'E. 1:111'L'1. 776/11 ..
Eldoret, .. $115
415 380 '11.} '5
75 .'1-1..:Ff1:.'l
34,560
£121.12?-
C.2025 1'1-1.1311151L:
Five miles W. 111'.1"';11L1.L1re:.1'?11
of Eldoret, 761/11 .. .. 11-114
108 75
"1 24
'.1—'1 '.—"1'.-'-1i'11.l
14,400
‘1'-'.21'1215
*C.2026 H111: miles
Five 11111-e W. ‘1‘1'. of 1111:1111L:'- 772/1
111' Eldoret, '72 1 . . ... 123
122 .12
82 3071.1.] 11.12.1111:
12,000
"*('L".2{.1117
*C.2067 Three 1:11:15: miles 11:11-35 W. ‘1‘-'. 1111'
of Lake LL1'.-LL': SOL-51:111.
Sergoit, 111. 8566 113.1111 .... 41111.1
400 ' .“.-'11
390 {'11.}
60 4.11111]
4,800
C.21‘7.11'1:-'1'
C.2068 Three
Three miles :111':e~'. NW. 711'1‘1'. 1:11'K:'11'1111.1.
of Karuna, 8344 1171-1-1- .... 215
215 .'35;
1'.“'-.' 98 1..-1:1 .711}
30 33151111":
3,600
C-ZH'TS
C.2078 Tin-'1: 11111:.5
Three miles ESE. ESE. of 1111' Nel's
ELF-'5 Bridge, 11111'111'5113- i.'8405/1. .':--1|I'.‘."1_ 1 . .. '60
.'-1'1 —'1'-.1
49 26
Zfi'1'4'.111': 9,120
{'."-21:17:21
C.2079 '1'-.11.:1 miles
Two 111125. SE. 51'. of “H'el'e Bridge,
1:11' Nel's [Bridge- 1'8405/2 1-11.115 2 .... 4.1.1
40 '1."
15 8:1 4.5111]:
4,800
"'1'-"211311111
*C.2080 '1'11r1L'L'. miles
Three 11'1'.L-".-'1 ‘51:.
SE. of 111' Nel's
7111:1'11 Bridge, BIIn-IL'- 6498/1 121—‘1'5115' 1 .. . . 131.1
130 41.1
40 61.'.'1 ':.1'III.'.II.'I
12,000
1':-21:11:11.
'C.2082 [-'Four
.-1111- miles 1111111. W. 11.-p 1111 111.111.1111. 1111:?
of Eldoret, 6107 . . .. ... . 71.11
70 1 .'--:'-
35 31
24 133-111
5,280
(1211:5113
C.2083 'I'1'1.'L:1 miles
Two :1‘1111311 SW. F.1‘1.‘1'_ of ['1‘-1".t1di'11'133'1.
Eldoret, 1'1—'1'." 8149 . L ... . 51
51 .'1'--'
39 1:1
25 '.1'1-1131
7,680
1'.".2151'1'1'4
C.2084 11'111- miles
Four 1'1' 1 13.: 511111.
SW. ofEKLiL'MWUL-‘I Kachouwat, 1. E11713 1
902/1 ... . 11.1
83 -- - '1..'
Nil
('.'.713111'13'
C.2085 1".-51.1." miles
Four 11:.1'.L.~'1 SW. 51‘1- 111' 1111111.“?"11.1".1. .11. 902/1
of Kachouwat, 111.12 '- .. 21-1]
80 - - ‘11'1'
Nil
1.121.151:
C.2086 '1' '11. 1.1 miles
Two mi:'1': SW. 5".11‘1- of 1.11 Kachouwat,
K'L'L-Lt1'1Lt1'L1'111'L11. "-.-"i 902/2.'1'.'.' .".' ... . '1—111
140 '1.-.1
70 .'1.;-
35 31:11-11
5,760
{".'.-71.11%?"
C.2087 . T-:11111 miles
Two 111.1.-e‘:1 SW. .‘1‘1’1'- of 111'14.1111:1:'L1
Eldoret, 8149 111-111 .... .. . 1.111
60 .111
31 18'...\" 1: 11111:
12,000
{12111113
C.2088 31:1.
Seven L1:: miles 11'. He: E. E. L1.11L
of Eldoret, 11r1- .151.6/101 31.11 ... . ... . 1.1.11
98 -——— -— 711111
Nil
{'.'.21'19'1
C.2089 '.‘-3e1.'-L'-1‘.
Seven miles .'1.11e~1 E. 1" . of1. .".1' '.1:11'L:-:_. 6/101
Eldoret, 1" 11.!1 ..
.. .. 3-H
80 35 '11'1'
18 :"."'-11'1
5,760
{'.ZI..'1'-.11
C.2091 1‘1'1-1‘ miles
Five 71:151-"1 W. "1'1. of 1.1L1'L}-""1-'1.. 772/4
111' Eldoret, '_2 -'+ ... . ... '.'.7
II7 2'1:
82 .1—1
34 ‘.‘-.41.
14,400 1- '1
C.2094
('_'.21.'!".1~'+ T111121" miles
Three 111131211. ‘.1. W.. 1.11' 1'.1111..'1:'L‘:'. 1':-11.1"
of Eldoret, 6107 ... . ... . - No
71.1.”: records
21;:L'1."'-.' - -
('.ll..'1‘.1F
C.2095 '1'1'1
Three n11.'L'.~1 W.
1'1-'1.: miles 1111. 111' -11111'L'1. 6107
of Eldoret, 1"'-I|..'|'-" ...L ... -— 7111.1 records
No '1'L1L"1'.1.='11-.~: -—— -— —
1.13117].
C.2II2 1—1'-.'L‘ 11111.11
Five miles W. of Eldoret, 772/5 '1‘-.'. 1:11'1'.1111:1:'1_'i. 7': .F ..
.. .-
.. '53.:
122 '-..1."1
98 _'1-.1
30 1.21.11 '1
1,200
"(ill 15
*C.2II5 '1"-.'-1': miles
Two r:1:LL'~'- S. ‘5 1.11:"
of Nel's BYE-'31:. 1'6498
."‘~L'1"1 Bridge, 1—1'21'1 ... 2111.1
200 1111
80 11'.'.1
10 1'.} '.'.'11'1.1
12,000
'-"I'L'."..'_‘:'-—'~1Z'I
*C.2540 _1_-1'1.- miles
Five '1 . L 1 NNE. 71171. 1'. of 1':'."1'L::"L11:1.'
Turbo, 4479/1 4—."1 1. ... . '_'1..'—5-
204 '..'-—‘1
184 :11
26 1: 11.-1.11.1
16,800
1.251114
C.2609 1"1:1111' miles
Four 111:1-L11'1 E. 1'.. of 1 1111:11'1L'1- 734
111' Eldoret, '.1—‘1 ... . ... 2711.112
231 85; IIO '.1: 1".-1"
64 '1'-'1.""1'.'1'.'1
56,000
C.2610
['.'.23'1 1'1 '1'1L1L'L1 11111311..
Two miles NW. of Turbo, 7446 .. 711'1"-' 111 TL11'1'..11_:1 74411 . . ..
. . 100
11.111 _'11..'|.' 88
30; H11 26
211 1"-1i.'l_1:.'.Ii.'I1'I
60,000
1.7211514
C.2684 T1111".- miles
Two :1.:-.E'.L'~1 W. ‘1'1. of 111' Lake ."-.'~-L'1'_L_1:.'11.. 883/R
.L'1'1LL' Sergoit, 1:11.7- 11’L .... 71.91
354 7141.1
340 1'.-1
49 21.111111
28,800
|1'.:1'1':-'-.-"'
C.2699 H1- L: miles r1111": NNW. 713111.121: 1.11.10.1..':.. 15' :1"-1'I-i1 '1 .. 1.11 '.I'.1 '12'1511!
Five of Eldoret, 6500/1
.. I 242 231 10 72,000

'_'1'1. "L11 -111: ':'L'.:=.-:.:1111_1:I

*Bore-holes reaching BasementH:'-.=1'L-1:.-1.e1:1 1‘.-131113.111
System rocks. 1'11L:.'~'L-.

. -' L. :L " 1.. 1,. ,...,-".. ._'.... L. -...- ':. .' .

Lake 1—11: this
F1L':L1111-.. For
1.111;: Sergoit. I—.
'..1..-. reason 1.111re-.11L.11L.-1 drilled
1-L"L'-.-.11L1. bore-holes L11.::-.L to
1111111311 close 1111- west
111 the L11 the
1111-11 of 111111;.1
1.1L- Moiben
1'1-11111: and
fault 111111 its
11.-1 accompanying
L-1L':L:1.11'11'1111-. 1311313.: escarpment
L'11e1'11'1111'1e111 11113: 1111613: to
are likely 11.1 give
3.31111: low
1011' yields.
311211111.

111171-1111 1'of
West 11' Sergoit
Hel'g1111 Rock 111111;}; the 11:11:. metamorphic
111e111111111'p111e floor 1'11'11'1' slopes
.111'1pe11 downwards
111.11.1'1:1‘111"L'11'L1:'1 to11:1 11a depth
depth of 1'11"
nee-1'11 350
nearly 3151') beneath
1113111211111 the 111.1;- lava
1111.11 surface
surface in 111 less
111.15 than:1111.11. three1111'ee miles;111111211: further1'.'L11'111L'1' to111 the
1111:- west,
.'1LL.-
111'111'1'2'1'1—21'. 11
however, it rises 111'1-1311'121'11111211'. 131.1
11111311 progressively, so that the 11111111101111:
111111 the phonolite thins 111111.11 to 1111111 100
11:11.11: than
111 less 11211.1 feet 31111.1:-
11:121. close
1L'1 the
to 1111;111:1111111'11111-1: inliers
111e metamorphic 1111112111 between11e111ee11 Leseru Leaem and 711e1'11 Bridge,
£11111 Nel's Bridge. (Fig. 111311218 below, :111L1 Fig.
111211.111: and 1'1-1L1.
9.' 1'1 11111311111.
at end). Movement :"1"11:1-.L'-1'11e1:11 of 111L11L: at
111' water 11113113111:
1'1: the base of 1:11" the 1311111111111131'. is,
1hL' phonolites 11'1- therefore, 131111111111
1111-311.1'L11'e. probably
111:1'11r'L'121'1 towards
deflected 11:11.1.11'11-1 the 111L- south-west
1L11111'1—'1'-1..':1~'~.‘. in
1:1 the
11113 area
1111311 between
1:11:1.'-.'-.'eL111 Soy11111}; :11111
and Eldoret. 1"..1L11.1.1e1. North
711L111 111'
of
F1113. the
Soy 111e lava 1111111 is 111' gen-31111131-
generally less 1L-.~.~1 11111.1
than 250 2:111 feet
112131 thick
11111:}; and 5111111111: the main 11111111 1.1111L11'
water 11L1pl1131'
supply lies 11L'11 L11.
at
111.111.1111 200
about 21.111111:feet, near 11:11.1: the 11:1: L'1"1:11'L'1'L1
contact 11et111'1-L'11
between the 1111': gneisses
3111135111211 1.11" of 111;: 81111-111111 System
the Basement $311131“. and and
thin 1111;131:1134 basal
111111 overlying 11171.1.-
-'. .1'L-1.-1L'11 tuffs.

TL: the
To the north11111111. and
and 1:11.111
east 1.11".E11:11'.'11'1:'1
of Eldoret 1111': the 11:1111 1111L1L'11L1111 111'
total thickness 1511111 probably
of lava 11111131113113: 1'exceeds
:-11313131111
I.'l'.| feet,
500 1'ee1.1:'1111.1
and the 1111: main
main 11111111'
supply 11115.1111L'1:
of water 1'is
1; 11.11.111.11 111111111111
found between 11113 113.:p'L'1
the upper 1111-:1
and 111111;."
lower
phonolites 11121-11115. of
1'1: depths
111'1..'1:11'-E?L1:-1 at 1.1-L'1'1.'-.L'e11 250
111 between 111111
:11 and 41.11.21 feet.
400 11321

15111111111111: water
Available 11111111111131; from
11111131: analyses 11111111 1111': 1411-1111131 'area
the Bldoret 1'1-11:111.: VI)
L=11:'L-:1 (Ta'ble 1111112311: the
‘1']: indicate 1111: '1'-111' L'- 1:111L1-
bore-holes
'LLrL
are 1131.1
liable 11:11
to "11:11:11 3.11:1: L11:.11L '1'1L'11L'r
yield potable water 1:11"of 11111111315111: 1111111111111}? with
moderate alkalinity 1.111111 :11
an 111111 1131111112111 11'1—
iron content fre-
I"?

". 1.111e111131'e11eeeL111L1
quently exceeding 11'1L the 111-1111111111:
desirable 1'1:L1.11.:11'111111
maximum L111 of 11.3
0.3 1:111:15
parts 1112';
per 11111111311.
million. 1311111115111:
Fluoride 1111111112111.
content
1:1
is 31311111111131-
generally less 1e11:1' than
1111111 111111“:
one part 1111111 per
per million,
11111111111. 1.1111
but 1111131'
may e.1LL'L'L'1'Ll
exceed this 11111.1 111111111:-
figure, :111 as in 1:11.1'.11[L'1:
water

....
 TFF' 1'51 1
'1': 261t C 1266 C 1346 '..?
C 1905 I Li)! "r'i 'I C 1074
ELGEYO f... _

E.
FEET C
';.,n,wr.-1in ! '1. '
- HAIBAGfiT
____ '..... _d...... e. = X'
D
[.._ Suh'h'h". |--H[’.-" 'LH', ram-mi

fin:
X ISAGA1

I
0 " "SAWMILLS=-

-.J
Sub~oil,lateritic gravel
M~EN

__L.._'.-_IJ.__--_
,
SO

100 ~~- ~- "

~ §
[
LT;
FTP—J“
I l..],‘.-l2u'-!' drum: Gent-L. Peoneiute
LJpperl,JasinGishu Phonolite, -

159
~ ~w., "","-.;

~'.'.'..~~'~
,
~ .7"! L:.':WP" Llafiin Guflr. Phannhte
Lo,!"erUasin Gi.hu Phonolite

.
200 WC? Tu”! ."H‘Ci HI'ITE- W lewd FIT wineh
[1---~ "~-W

__-_
Tuff. and grits '--w L~vel at ~hich
watt-r was. struck
250
---FJ- ~, ~ ~
L J 'u"'."r&.‘«.rl".eled lane-559‘. water was struck
LJ
'

Lg;
Weathered gneisses
300 SCALE ~' , rx-xl G '
5S0
I 2 5
,
4 5 MILES
I
~ ~ ne15ses
—_-_I—-__a——-

400
u'"_1_3'?-?
12 raw-fawn '-'. __ i. 254Q
'2 (: 1065 SOY '96LC 211~C '82L--C 1904 53.3.-.
C 1637 C 1577 -.- w...
C 2086, .
'1'.Irfr1f.r.‘:—--- 1'|!'r
.II

r_C C 'C

a
'
H~BH'LHHE
~~66~D'S T

l
2L-
y 0
'- Surface-:-

. I._____.__
y'
~
‘-..[J '
\ -w w -w
—:.T—_'""" .

50
_

.",. ' :..:

i
' "
"

~
,

lOO ',',

/ ~ \ 1 -w
1

I
/ /i.,~, '. "

-- 7 i::,:-w
E

x -w " --""",
/
__ 1...

IS0x~ ,/ x "-' ~, --.....

~
,

~
,

-w
——|-—

.....

200 [ x =w ,

~
I'<I/'" ~ ~"
'

:--0::::-----.

91?
0\
250 : u/ ,/ x "-

300
x
~ ~ ? :' '; i
SCALE
-" fl- ” ' 5' HILLS-

550 r.
'/ ~'~'.~ L!_L_I,oMILESI

"'-W'
400
ELI-3'?___.._ _ II. 3:517“?
._ ..______ '1' _. -7; -“ '3'35'3 55532..
I.-.

Z 0 -S 2550'
‘.- NDALAT C 268~ If 12H
. 1.— Flfi'l
126~ ..; 20
cI: 2026
91.. -._l EEIF'E C 2022 I1. EIL'IEi’i
_. Surface.
Surface - -- E
Z',
E:ELDORET
_DL'.J-Hi: ' ‘
so
'<. -w \
'\-.

100 ::. m
-<-w ~ w- ~ ~ -\w 'D~w 'i:w ";~
:.' -"
."- '.
- 'I:

ISO
~,,' -w
,,-- ~'
' " \
200

250.,u
'" \ .-w
0 1 2,' 3 .
SCALE
s' 6 7? 8H 9
'1 10
1-3 MILES
HILE5

500
:‘m L.-
\ , , ,. ""'! ,_._ J

J59
359 \ . . I.“ W

r:'. I
c 400 ,
_F
For inn-es of
For lines sEetmrI see
(if section Fug .7v‘ and
see Fig, “m genlng
are: for geological seen-amt. see
:‘al sections Hg ‘3‘
see Fig, 9
Hg. 88-Selected
Fig. Heleeied hnre-lmle
bore-hole Heetimw
sections frmn
from the. l-Llrlnref :n'eu.
the Eldoret area.
 47

:tttaltaetl
analysed from [.'..l:.t'_'--f"r. Two
L‘Ul' Le-h-Li't'i; C.1266.
{stint bore-hole leer Ltt‘it‘ilyriee
analyses of ‘-.ycll—tyete:' from
mt" well-water Mytibett. and
from Moiben, and
TIRE]:
river ".".'Lil.t_‘l'
water ;E'L_'H'T_‘r
from L l'l-JL‘H. T'Lll'Lieti
Chebororua, Lt':!-.-_'t..-l
contain excessive CELL-‘HHKL. amounts Ll;
{LI-I'lCUIILH -LL'll
of iron t‘rl l'eh
which Lil—1.
can DC”-
be
h. 5....3 ._,.,_ .. 1-
'.,." ’,. . . .
Htli'..-_i!_"._-.
suitably reduced
.
retttrc-Jtt I ' 1 ..
by
. .:;.I,.._. «9
!_"|_y LLelLii::1..r-a
addition of t-i lime .' , ..
l.t-.te tr:1 produce
to L'LU'...L.-..-'-._- 12H...-tahle
potable bate].
water.
"1.51
‘1'.-'-.t=:t.‘. VI-WATER
TABLE ."‘r.'-.I‘r'.~iI-.~; FROM
‘t—‘rJ-tlt ANALYSES 134+: ELDORET
.F-".-L-'-‘-1 THE .-“.JtE.-t
ELIH'JRET AREA
r "
(From I:
Records ..gs‘ the Hydraulics
of ls-s'it I}:'_."---.'r“Liszt-1:5- Ministry
Department, ."mt’.".=ii.~..-‘.r_r of
rig" Works)
Elli-ain’t

PARTS 31' '

he MILLION
.Hrr .a PER x
Sample No. a.” r .r 'H RH.
H |. Iii—I.k\. 3' L

tCI H()
_ — — ———_

KC):
—_

.., pH CaC03 NH3 S04 NOz 1::

Fe 5111:};
SiOz F
--—-_

l“

RH. “-..S
RiVERS

:42"—
2497 .. — --!
7,0 —-If'
40 "I- | "i
0.18 1i it
tr circa
pres 1-?!
2.9 Ill
20 51":
0.2
“if ‘
857/8 .. 7'5
_'f" :i 't
206 I'F-H
0,30 5L“ trIt Free
pres 1' '4
0.9 :t]
26 til-r:
0.8
HIT-31f},
986 .. - 7-1.
7'1 -"-'
62 ."I-Il'l'=
0,03 77 tr prick;
pres 't'l-T
0,7 "ll-l
20 [ll-5
0.5
1t‘t't: : y AND
WELLS* fl.“
BLIIRL- . 1...:
BORE-HOLES
l..._. _ _—
llilf‘TI‘
1055* .. 5.8-._ 50-- I I
0.64 r 6 nil.'- __.._
£.-_.._-
pres “2-:_
2.5
._. "-'
36
.‘l'r ..-..'
0.9
t." I:
-
1tI:-e=='-
1056* .. r
6'3 l r ~
113 1
1.9 1-,
14 . r.
nil :trea
pres .i-l
3.2 .t
30 0.5
be
35th.
1806 .. :~ ti
8,0 jibe
264 [I
tr J "
65 ti
10 nil ICE-5
0,5 30
311 6.3
bx"
”33
1833 .. —"‘*'
7.8 l'i." r
104 '5 I
0'12 1r i i'
nil brew
pres tr'
tr 5t]
50 U-Z
0.2
i It};
1194 ., 7,5 -_- 90 . I I
0.11 .r l
0'16 7‘ tire»
pres 0,4 I-—? If-
25 0'1
IL?”
:32
232 .. 6,7_ 133 .
0.14 . l:
15 13 It
nil 0'3 I-F 3t!
30 I..'!-i‘~
0.8
4""
522 .. a
8,3 :~-
85 -
nil 1 nil ‘II
nil 1.5 'q- HI
30 [II-H"
0'2
SI-‘RIMJS
SPRINGS
273‘.)
2729 .. F --..'r
5,9 87“- I..- T .:'
0.25 4 .r;"'.
4,0 tr 111'.
nil 5 '2
3.2 lb:
18 U-b
0.6
1b: .., , -5 .-..: 1 ti - : 4 -=;_i 8i; 1' i'. - -—— I...Z--‘
-
-
202 6,3 60 0.28 4,0 nil 0.7
I

2-HT
2497 (ihehbrertia lliyer S.
Chebororua River F. Cherangani
I'._ .:er;'.-:'rg;i:ti Hills.
ll iie.
be???
857/8 Little Riyet‘.
Netiia River.
Little. Nzoia
Elite
986 Sosiani Rite-r, Turbo.
Scisirtiti River, Turbe.
luff?
1055 Eirell "A"
Well trailing: Centre.
I‘t‘leib-Jzt Trading
“A“ Moiben belittle.
Elle—Ft
1056 ‘t‘k’ell "C"
Well "C" Elijah-eat
Moiben Trading Tt'ti,-.ll|'I'-_J. Letttr-J.
Centre.
lifitlb
1806 Bore-hole fill-Yeti. Moiben.
B-L'HiJ-l'lfllt‘ C.1266. hlrra's'veit
lei?
1833 Here-Etbie C.2025.
Bore-hole Fi're miles
L'.2|..'I|2.‘—-. Five W. of
it"lliliri W. Eitittr'et.
est EIdoret.
ll‘fi—l
1194 Bore-hole (IIIEJIH. Five
Bare—herie C.2540. l-iy'J miles mile-r. NNE.R \i—L. of 'i'til'bri.
r‘ri' Turbo.
233:
232 Bere-heie C.1426.
Bore-hole (3.1426. Four Fear miles ririles NE. NE. of Eltleret.
ei‘ Eldoret.
5-22
522 Bare—hole C.2688.
Bore-hole {_'.3r’rr~ir~'~'. Two
i'tye- miles mil-e5 SE. fit-I of Ndalat. \J.:.‘.it.
.2729
2729 Spring S.
Spring S. of .‘xieibei: Post
e2" Moiben Dillee.
l’n._'-:~L Office.
2-1):
202 Spring he: Moiben
Staring. near hicribeit Trading 'l matting Centre. (_-'L"f'!'_|'-.,".

13. Hydro-Electricity
13. Hydre-Eleclricit}
The Sosiani
The river at
Seeiani river Selby Falls
at Selby utilized to
is utilized
Falls is drite two
tri drive tttrhe—alterrtaters
ttater turbo-alternators
tee. water
each generating
each generating 180 Hit") kilowatts
hiirgeyatte of of electricity
electricity forfer local
lecel consumption
certsumptiee in Elderet. The
in Eldoret. The
riyer is
river iii controlled
controlled by by aa weir
tit-eit- immediately
immediately aboveabeese thethe falls. thus providing
falls, thus preyidilg aa normal
nermal
working head of
working head it'll] feet
et’ 100 abm'e the
ieei above intakes of
the intakes the turbines
iii the which are
terbihcr. which fett'
hritereci aa few
are housed
hundred from the
yards from
hundred yards tee: of
the foot of the fella.
the falls.
Elsewhere in in the area. two
the area, hieatiertri are
the locations t'at'critrable for ter set-all hydro-electric
I-u

Elsewhere are favourable small hydro-electric

schemes similar in
echemes similar acetic. to
in scope that at
tb that at Selby Falls. but
Selby Falls,. but in each case
in each case the cbet ef
the cost water
of water
control weultl be
etmtrel would higher than
be higher than those incurred at
these incurred at Selby Falle.
Selby Falls.
The first
The first favourable
fatettrabie --:ite
site is It; at
at the
the eeethteeee
confluence of
'l
the. Sosiani
of the Stiiilfll'ti anti" Ripkerrcrt rivers,
and Kipkarren riyere.
ripptehimately five
approximately the miles
miles etzr-Lith-e'ee:
south-west et' Terbri. Here
of Turbo. licre the the flew
flow tit of the Seaiani is
the Sosiani is more
mere
than twice-
than twice t'hat
that at Selby Falls,
at Selby Falia. Since.
since it it is
ie crimbincrl
combined with with that
that of (if its
its tributaries,
tributaries. the the
Sergeit andand Kaigat.
Kitigai. For
Fer" about
abetit ae mile etiie before
etere reaching
reaching the the Kipkarren,
Kipkarrert. the the Sosiani
Seuiani
r3—

Sergoit
desceeds aa steep
descends steep and
and rapid
rate; section
Sic-ether: above
abe-'-.e which
which weireel: control
crtntrbl would
tyULJlCi provide
preyide aa working
tt-‘bi‘kiitg
I head of
head cit" over
byer ltlfl
100 tee:
feet let
for :1.a generating itatieit riittzateti
generating station situated bear the confluence
near the certilecncc at of the there.
the rivers.
I
r.. The Seceittl
The second possible per-aibie site 2-.ite is
in in
in- the
the upper
upper Moiben .‘yteibch valley
t-allcy about
abettt threethree miles miles te the
to the
ytiiith of
south bf Kapsiliat,
Kttprcllléit. where where the the Moiben
Nether: river rirer passespair-reg through
threegh aa eieep. deep, narrow Itarre‘e' gergc
gorge
with aa gradient
with gradient of ei' abeti:
about Ebb 300 feet "eet perhe: mile.
t'riie. The
The yrriertte
volume of til" the riyet‘ here
the river here is ii; probably
probably
t ban that
leafy than
less that. of re" the the ‘itiairiiti
Sosiani at i-iltit'rrei. but
at Eldoret, bttt is iii eel
well ittairttainetl
maintained lJCCJtLtSe
because of ef its itri proximity
prealmity
... lt_'." the
to the forest
t'ereet area. area, and and -t_l..;?t"rlt'llt'lg
damming between between the the rockreel; walls
wall-a ef of the gerge above
the gorge abeye the the steepest
eteebewt
*L‘e'. 0."!
section would --'-l.."..!lel augment :LLttcl of
L!!:_:_.'.i".'":-el.i the head Ul water allt‘ttrcle‘tl by
fielcl provided I'M the .LI:r-:-._-:t.l:_'[.
xttllc‘t gradient.
Il'tC valley

dI
...
'i'

-1. 11';
48

'1IIiI-IEEIEI11'1ilfH
VIII-REFERENCES
IIHCI‘IEI'. W.
Bucher, '11. H.,
H.. 1957.-"Deformation
i231“? "ILL-:1... :'.1.1'.i:‘-I.1. of
LEE the
1i1L1 Earth's
1..1.'i 'E'I. ICrust".
I‘LL-11

IE11I|111'I'.I. E.
Bullard, I1. IC.,
L .- 1936.-"Gravity
'iI-Js'II'I. "I.’_i1'.';1'1I-.}. Measurements
111:111111L1111:11:.~I in
.1 East
E .1211 .-E1ii'.'1.':
Africa". Phil.1"1'11'1'. Trans.
11' 11111.1. 11311:.
Roy. .‘1' 1..I1-'..
Soc.,
I-I.'..II'.-151'111. Vol.
London, E111}. 2.371. 11111. 445-531.
235, pp. E—LE-i'If-Q.

11,1.”1'1133.
R. W.,
‘EI'C'hLmEIZ R.
*Chaney, - "'1'I1::'lf;-.;"_-.
1933.-"A Tertiary floraIII'JI'EL from I_"'_.I:'I:I11'.:1".I'1XI-I.;1."
i'1'-.1.*11 Uganda". Journ. Geol. XLI, p. 702.
LIC—SII.I.CI.1—-.
de Sitter, L. U., I'JE‘II‘J.
L... 1956.-"Structural 1.1.3.1113:—
E‘II'EICILH'JII Geology".

IJI§11L11_. ']—'..
Dixey, ]'~1~ESI.- "T1111; 11.11.11T11I
F., 1948.-"The Geology 111' 31311111111“: Kenya".
of Northern 11111-111311". Report
311-111111 E141".
No. E5.15, ELI-:11].
Geol. 51111.
Surv.
K111113111.
Kenya.
*Eskola, P.. IEI'ZI.I'.-—-“'
*"E11I111II11. 'P., [111111.11 of
_"I.Ii.'11.:1'.'-II Facies
1920.-"The I11: Mineral III-3:11.11". Norsk.
111 Rocks". 11
.EI.'1.1.I‘1.II.'. 1'Geol. Tidsskr., fi.
1’11]. 6,
'I'.-"11'11.I'1.I'.. Vol.
11131-11111.
pp. 143-194.
pp.
Francis. £3.
Francis, H.. 1956.-"Facies
G. H., $11511. ”T111131 Boundaries E1.1:.111-:I-.I11E11I. in
111 Petites
F.11111-1 :at
. 1111: :I‘IIEILIILI 3.-_11'
the middle grades 11I.I1::1 1.11"
of 111231011111
Regional
E11E111111111'11h1-Im“. {31-111.
Metamorphism". .-'I-'.1'.I1‘-'.. Vol.
Geol. Mag., E1111. XCIII,
ERIE. III. pp. 353-368.
I ..'

I'jI'I'It. '1'1’.
Fyfe, W. S.,'11.. 111111.111:
Turner, I7. F. .I.
J. 111111
and ‘1-'I:I'I‘1111.'Ig1-.-:1.
Verhoogen, .I.. 11.15111. ”."1I1:11'1111111'111EI11'L: Reactions
J., 1958.-"Metamorphic R..1.I-11111 11111.1
and
I1'1c11111'1111'pI1E-LI Facies."
Metamorphic Elmira." I'E.I:.111i.
Geol. 51111:.
Soc. 91111111.
Amer. Mem. NIL-111?}.
73.
Uihmn.
Gibson, A..—'I1. B.,
[I.. 1954.-"Geology
HEE- "IE._1L'-11I1I§'_.' 11;"
of III-.1 EII'I._'I1.IL'-"i:'~.' Falls
the Broderick I_::3.'1_I'. .-'I.1'L-.-.'I".
Area". Report IIIL‘121111'1 No.
E1411. 21"1.
26, [._ICI'JI.
Geol.
511111:
Surv. Kenya.FEE-111.11.

11' 1'1'I.=I_.:I_.11I"1.-. _I.

Gregory, J. W., 11921. "Thu H111
‘1'II'.. 1921.-"The '1'11I'11331'I'I 111111
Rift Valleys Geology 111'
and ILI-.=-:'1II.1I:1 of East _-
.-‘I11'1'I:.I'.1".
'1'.'-.:-.II'. Africa".

Hess, H. H.,
H1111. H. 11.1515. - “.‘1111‘p111'11i111:r-II. {.311
H.. 1955.-"Serpentines, IIIL11. 1111.!
Orogeny and Epeirogeny" "Crust 11f
E11 “Cm-IL
EIHIIIIIILJI ' in of the Earth".
1I11- Earth",
[31:11].
Geol. Soc. ”-111 11:.“ "51.11.11.1113:
‘111113. Amer., Special Paper 13111111111.62, pp. .EI‘JIIJIII'IT.
_. 111.1. 391-407.
I-II.ILI'1'. (Z.
Hoey, C., 1955.-"Early 13111151 1.111
1955. "I'.'.'II'I11' Days on the I'I1'1i.1.1..11". Kenya
the Plateau". l1
.FI..'.I.-'I1_1'.I."1 Weekly .‘1'1II111. Agric.
News, Suppfu
.-‘-I1gI'I'-:. Suppl.,
11g‘1. TIE—15""
pp. 74-77.
JI:JT‘II1‘1;._1_11.I.}..I..
Jennings, D. J., 1964.-"Geology 112-1" the
."_-..'II!'_I~'I. "(_IL-11II152j-s of Err-.1". Report
I11;1;1-I.1.1i.1I:'1.I'I111'L-11'.i Area".
II'IL: Kapsabet-Plateau FIE.
E1111 63,
III-11111111. No.
(31:11I.."1111'.'1
Geol. II._.'-11.'_111.
Surv. Kenya.
Kay, American {..113111131'1111i11':-:I".
1951.-"North .IE11'I'11il'311111"
KL'I'I'.M.,.II'.‘?I."E‘11I."I1'ZI‘I Geosynclines". Geol. '1 i""| ..EIII..:-11‘I.
5111-2. Amer.,
1'_1'-.-1_'-I. Soc. Mem. No. E1111. 41-3.
48.
\ Krenkel, E... 1925.-"Geologie
IILI'LInkLII. E., 1171.1 Erde",
1'925. "1.11:11I11gi11 der 1.
3'11}. 1.
11211.1"- Vol.
I.I_1’['*1L11‘11.E..-E1..I‘1".*EE.-
Loftus, -"I'I‘11111"1-'I11_'111———'I"-1IL'.L_IE1E1'I'.=.Inez-LI".
E. A., 1951.-"Thomson-Through Masai Land". E.A. E'. E1. Lit.
I.E‘.. Bureau.
I_I‘11."1.".—.1_].
1112113111 J.
Miller, .I. III-I.. 1ELISE-I1.——"I'1.EIL'.11I11I:E}. -;'I|
M., 1956.-"Geology of the‘.hL- Kitale-Cherangani
IIIEIIJIEC—I"111:1'2-111g'1'1111 Hills
IIIIII'. Area".
91111-11". Report
III—{122111111 E‘I1'I.
No. 35. .ETI.
I.“_&1:1_1I.
Geol. 521L111.
Surv. 3111111511.
Kenya.
E1III1‘LE. G.,
Milne, [I.. 1.113111.
1936.-"A'.EI. provisional
111'131‘1I1'1I.111:I§ soil --.-:.'2II map
'It'I.'II.1 of1311' East
I 1.11 Africa".
“1515.11". East
I111: African
.'1;'."i1.:.111 Agricultural
.-'11II'31:1|I1L11';_1I
P1121113111'13h Station,
Research 511.11I11I1. Amani,
.-"I111"'.-111'II. 'ITanganyika
.11'1-._:.111j.'3'11'.1 Territory.
'I'1I1'I'f1i11'1.
EIIILJIT (Maute),
Muff ['.EIII1111E121. H.II. B.,
II.. 1908.-"Reports
l '_.'1|'.__'i}1'_ "IE-1.9111111 relating |"-.'."IHIIE'I'_._." ':11
to 'the
:I"-.-'.E.‘ III-CIEIL'ISE.
Geology 111' III: East
of the I.I.:II1|.. African
.- 1'1'I1:1'111
I‘EJUICL'-I."I].'_'1E
Protectorate.I... III-III. I{C_1'.‘-. Misc.
Col. Rep. .'1-I'--"... No.
IE-III- 45
E-IE ELI
(Cd. LI. 3-‘2-7”.
3828).
E1111? 111'IH'IILIII.1:I1_ R., 111 .‘1.- IE- IIL‘1. L'I1.
11‘.“ 1933.-"Notes --| __ _ _
on [111:
1_ .'__- ' ....
..1-_'..-|I.2-_;1L'_:: E111LLL':II-I.|1"‘I.
I.
_.ILL'.L.!IEIL?1
Tectonics 1!.IE1LI
11.-.-'.
I_.,_..

--.- 11— '

Murray-Hughes, the Geological Succession,
I{;-I]L1:“L EU- 3. {ECU}
and
I'LC'E'.-_ (“e
ECGIEUIHIC {.tLI‘IIL11 1zf'r. DIE IIEE ".'-..-._'-‘-I'.;"E';‘_ EELLEEI ._..I'
Economic Geology of the western half of Kenya Colony". Report No.3, Geol.
K:I.1f.‘:'1.
E11111. Kenya.
Surv.

'I""E'-'1.-':E-
Prior, T-I 1903.-"Contributions
G. T., 151: Petrology
111 the
11-1113, ”(I-11111I'IiiI11111.::1':~I to 3111.341 East
._1;' British
IEL'iI'L-IiI'Ig} of -1111'.I:II..I1:.-"
.-'11':'iL‘-.I“. Mineral
I".::.III Africa".
111E. XIII,
$111.13.. Vol.
Mag., 331-1—21'1}.
11.111. 228-263.
E-EIII. pp.

P.1:[.L__‘1.I.'H
Pulfrey, W., 1960.-"Shapc 11:'1}11'.
I'JIII"-----"EII‘I1I|.11= of the Sub-Miocene ’r.:.-I-'.1II1 Bevel
ELIE-111111111111 Erosion B11
;11 Kenya".
13111111.? in Bull. T1111. 3.
IEIIIE. No.3.
{.IL‘EIL11
Geo!. Surv.111 Kenya.14.111511.

Hunflficrg. H.,
Ramberg, II.. 1952.-"The
|'E52.—-— ' IIIL" Origin
0113111111 31111111111111111111.‘ and
of Metamorphic 11111.1' Metasomatic
"IIIL1111111111.:1 L Rocks".
R1_..'I1..I'.".

11.._.__ consulted
*Not I.'.:..L'1I 1
in I.-.I_I1.I‘I-..:.
original.

l
I...
 49
49

Httt'lthfllfi. L.
Sanders, i... D., Niki—Est-- ”{Jidhrgy of
[.1. 1954A.-"Geology {El the
151:: Kitui
Hittii Area".
.-‘~.I':::':". Report
Rupul't No.
Hm. 30,
311. Geol.
Lieu]. Surv.
SL111;
K-'*It}-';1.
Kenya.
-, _ 1954B.-"The
1954B.~——"'1hc Status
btttttlr; of
L111 Sillimanite
Htittr'.1;.u'1jt-: as ;t:~.:. an
=.-.n Index
{mic}; of
mi" Metamorphic
flickiniui'phic Grade
{EYE-[dc in
in
~ the Kenya
the Kenya Basement
Bt'tiaement System".
System". t":'t"r.r.-’. .-’L'ft:_:«‘.. Vol.
Geol. Mag., E'ul. XCI, HUI. pp.
pp. 144-152.
144—152.
Hunt. 1..
Scott, l'~1"— "R_:.‘jt_'1l't m
J., 1932.-"Report i:1*~-.:-t:._'__r.=.t!'t'1n.-: into
of Investigations [Hm fitittgvljt'
Supply t‘sf t.ir11c.-:mn: pru‘tiutfflflg.‘
of Limestone particularly fotTut
the
the HHH'LL Pr'm'incc". Dept.
Nzoia Province". [31:132. gigrit'tilttn'c.
Agriculture, Hm“ Kenya.
Hattr'lc. 1'}.
Searle, '1... 1952.-"Geology
D. L., 1952. "Lharfit'agg. of
n? t"-..: Area
the ins-.11 North-west
htn'lh—x'ntw‘. mt" Hit-ttlc '[n'wns'hip
of Kitale Township {T111111
(rrans-
Hit-ta. Eigtm
Nzoia, Elgon and West Suit)".
and West Suk)". Riftfflttl't
Report No. M}. 19,
It}- {JCL_"'1.
Geol. Start.
Surv. Kenya.
Kenya.
ttcklettm. R.
Shackleton, Ii. '31.-
M., W44. "cun m1
1944.--"Report on thetho. {jamtt'wg}.
Geology of of the:
the .-*~.r-c.:1
Area .-*'t:'utmt1
Around :‘t-iatlitkiai.
Malakisi,
Huh-irmldu". Emmi.
Kavirondo". Geol. Slums.
Surv. Hang.
Kenya..11. 'lflrp:t:'izn=:r1.1l
Departmental Rep-tut Report {tmgfi-tzhti-ahed'I.
(unpublished).
-------_--
-, 194:3. "Geology ni'
1946.-"Geology of the1..-“v:- Migori
h—iigm‘i {hit-j hit and
Gold Belt and Adjoining
Adi-aming Areas".
,.-‘~..--;;.1_~;". Report
cnr't
Tim It]. 63111.
No. 10, gun: Kent-:1.
Geol. Surv. Kenya.
-, -. 1951.-"A
1‘15L—5‘fit {THE‘Ill—1111111Lfirl
Contribution to the t; Geology
.-:'-.' of 'the
=_=t-.: Kavirondo
Hta'airt'tz‘lth‘l Rift Tatum"
Rift Valley".
I:
it Journ.
Quart. {13:11- Soc.,
Geol. ‘x' pp.
3.2.15. ifCVI,
firm-z. Vol. "
ma. 345-392.
Smith. W.
Smith, 't‘t'". Campbell,
Cmnpbcti. 1931.--"A
|'-}_'%I.—— "-‘- if"|_:-.-;ji.itt._':_:itnt
Classification of Some H.311]; Rhyolites,
R!‘:3'L'-|L1c.-. Trachytes
"littchflcs anti and
i’ht‘nmiitCH. fro-“:1
Phonolites, PLLI'L t-E"
from Part of KenyaH:Ifi.j.';'1_ Colony,
."néunfg. with
with .1a Note
Hot: 011
on ELL-[11c
Some {.111 of the .-'*~.Sfitficizttcd
the Associated
Basattic Rt'wt‘krs".
Basaltic Rocks". Qatari.
Quart. Journ..t't-zes-zrrz. t}.:-r-.I.-'.
Geol. Err-5'2. T-ul. LXXXVII,
Soc., Vol. IKE Kip-"1]. pp.
Ling}. 212-25S.
Eli—ESE.
'I'I‘c1'tdttH,
Trendall, A. A. 13..
F., 'EgJSt}.-—--"'i'hu
1959.-"The tt‘npngrrgti'g
topography 'I_.":‘tt1t2|'
under the
the .rtti-t‘ihm'tt
northern part of the
“in": 111:
.r-" the Eudztm
Kadam tul—
vol-
canics
canics and {[5 bearing
and its bearing un Lib: t..:|ci.:ttit:-I:-
on the correlation L"'_
.""| -. ' '
tin-.1 peneplains
of the Wham-aim uJ' of snttth-cust Ligand-.3.
south-east Uganda
and
and H11:
the adjacent parts {If
adjacent-parts of Kent-'3".
Kenya". Return-.15..
Records, final.
Geol. Hurt. jgflmla- 1955555.
Surv. Uganda, 1955/56, pp.
pp. L33.
l-S.
‘l‘umm‘.
Turner, P.
F. 1..
J., 194S.-- “h'iineralagical and
1945.-"Mineralogical and Structural
Structural }'-'..t-'t_:lut[m1
Evolution nf of thL
the L'Tetamnrphi:
Metamorphic
Racks“. [Er-1.9!.
Rocks". Geol. Erica
Soc. ..-4;:+:.s?r.__.
Amer., Mam. Mem. 3t].
30.
--, and Verhoogen,
and 1. 1951.-"Igneous
5' c.}'at:lt'tg:‘:n. J., and Metamorphic
[5351: -“1311a3tl~Lt5 and Pctl'tflngt"
M:t:-‘..rnt2~1'ph'§t‘ Petrology".

Vening Meinesz,
Vening Mammy. F. F. A., 3%.. 1954.-"Indonesian
]P'r‘fi—ir-S‘tndt:r;:r.::~:.i.-an Archipelago:
.-'*~.:'Lthig*.c|;tgm: A
ft Geophysical
fi€tfi+13hjssECuI Study". Est-3'."
Study". Bull.
Cal-(III.
Geol. Slim. ..4.r'.J.'-:-'.I‘._. Vol.
Soc. Amer., V4.31. {'15. gm. 143-164.
65, pp. 143-1114.
—., 1955. --“|’1ttr+tic Buckling
1955.-"Plastic Buckling 1;t 111:": Earth's
of the [Eiatt'th‘i tTuHI
Crust:.' 'l'hl':
The flH'igifl
Origin t'tf
of Gflt'my'nflincau
Geosynclines",
in “Crust
in "Crust ofof the
the Earth". Gaul. 50:3.
Earth". Oeol. fln‘IEJu, Special
Soc. Amer., Special Paper
Paper E12. 62, pp.
pp. 3193M).
319-330.
H's‘fllker. E.
Walker, E}. E.,
F... 1903.-"Report
19113.-~“Re_purt. on
on the:
the {_'i-..=trlngj;
Geology of of" 1.11:: Etta-f African
the East Africa-n Pa‘utectnt'tt1_c".
Protectorate".
.-"tf1'it‘-a.. No.
Africa, Hi}. 11
H {(‘d.
(Cd. ITEQ‘L
1769).

...

....
G.P.K.2143~—tnt
G.l>.K.2243-1m-8/61 fig’tit

F“
.... __ ___..__
.-