The Drainage System of Brazil

Author(s): O. A. Derby
Source: Science, Vol. 5, No. 114 (Apr. 10, 1885), pp. 296-299
Published by: American Association for the Advancement of Science
Stable URL: http://www.jstor.org/stable/1761494
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296 SCIENCE. [VOL. V., No. 114.

by
bythe thesound
sound
arisingarising
from shaking
from rods
shaking
within
as fastit,
as fast rods
as
asthe
the within
iceice
will
will
permit, it,
permit,
theythey
fish until
fish about
until about
Mr. Andrew IIaddow, the engineer, lowered four the first of September, unless sooner loaded, and
eight-inch bar-magnets (placed end to end, with the then sail for home. During the eleven years preced-
south pole down) into the bore. The north pole of ing a 1874, about fifty voyages are known to have been
compass-needle in the mine moved first to the west,made; and the returns give an average of $27,420 per
and then to the east, of magnetic north, as the mag-voyage, which shows a large margin of profit to the
nets were lowered, indicating that the magnets were small sailing-vessels usually engaged in the trade.
to the westward of the compass. While the headingIt is estimated that the aggregate value of oil and
was being enlarged in this direction, Mr. Haddow whalebone already obtained is about two and a quar-
experimented by passing a magnet around the com- ter million dollars, and every thing points to a large
pass, and drawing a series of curves for positions of extension of the industry.
the magnet, which produced different angular deflec- The porpoise-fishery is extensively carried on by
tions of the needle. The compass was then placed the fHudson-Bay company; the fish, as they are popu-
successively at two different points in the heading, larly called, being held in check by means of trap-
and the deflections caused by the magnets in the nets on flats in coves where the tide rises ten or
bore-hole were noted, - at one point 3?o, at the fifteen feet, and left lhigli and dry when the wat
other 6-?. The two points were then marked on recedes. Last year the company secured nearly
the plan of the mine, a tracing of the magnetic two hundred in one tide at Churchill, atnd a much
curves just referred to was placed over each point, larger number at Ungava Bay. The blubber weighs
and the intersection of the curves corresponding to from two hundred and fifty to four hundred pounds,
these deflections was noted. Upon excavating to the and is very rich in the finest of oil. Formerly the
point thus indicated, the bore was found, being about blubber was exported; but the company has estab-
eight feet from the true vertical. lished extensive refineries at several of its northern
In a second case, in Australia, the diamond drill, stations, and now ships thle oil in casks.
in going downi three hundred and seventy feet, had The company also carries on a walrus-lhunt, send-
deviated beyond sensible magnetic influence, and the ing two sloops annually from Churchill to two very
search by underground mining was continued for productive walrus-grounds north of Marble Island,
nearly twelve months without success. Mr. E. F. where they have never failed to obtain full cargoes
Macgeorge then employed glass phials partly filled of blubber, ivory, and hides in a few weeks, besides
with melted gelatine, and having a compass-needle carrying on a valuable trade in oil, ivory, musk-ox,
in a lower connected bulb of the phial. Whlen these and other skins, with the northern Eskimo.
were carefully lowered in the bore to different depths, During the exploring-steamer Neptune's visit to
and the gelatine congealed, the needle would become Stupart's Bay, the Eskimo were living on the harp-
fixed in the magnetic north, and the surface of the seal (Phoca groenlandica Linnd), and had in their
gelatine would be horizontal. These two in(lications, possession skins of a good many harbor and square-
when the phial was withdrawn, showed the inclina- flipper seals (Phoca vitulina Linne, and Erignathus
tion and magnetic bearing of the bore-hole at that barbatus Fabricius), seals of all kinds being abun-
point; and a sufficient number of observations at dant.
convenient depths permitted the erratic bore-hole to The Hudson-Bay company has a steamier, the
be completely mapped from top to bottom. This Diana, plying between London and Ungava Bay di-
map showed a deviation of nearly forty feet at three rect, fitted up with refrigerating apparatus, and en-
hundred and seventy feet down (the point so long gaged solely in conveying salnon fresh to the London
searched for), and of between seventy and eighty market. Last year's cargo is reported to have real-
feet at the full depth of five hundred feet. A drift ized eighteen thousand dollars. Nearly every stream
straight for the indicated spot found the lost bore contains both salmon and trout in vast -quantities,
thirty-seven feet and a half away front its proper chiefly where the salt and fresh waters mingile.
place, and the bottom was found seventy-five feet Cod abound in the vicinity of Chudleigh, though
astray. This device has since been perfected and not up to the present time found in Hudson Bay.
patented. Newfoundland schooners even now work as far north
as Nachvak, and seem to be going farther each year.
The cod, though good, are not equal to those of the
FISHING-INTERESTS IN HUDSON BAY. Banks. While the Neptune was at Port Burwell,
TriE chief commercial value of this district un- both in going and on returning, tlle anchorage
doubtedly lies in its immense fishing-interests, teemed with cod, which were taken in great numbers
if we
include in that term whaling and sealing. by jigging fromi the ship's deck.
American whaling-vessels have for more than a
quarter of a century beeni conducting a very profit-
able fishery in Roe's Welcome, a large basin in
THE theDRAINAGE SYSTEM' OF BRAZIL.1
northl-western portion of Hudson Bay. The vessels
usually leave New England in July, and reacll THE
Marble
hydrographic features of Brazil are to a cer-
Island in September, where they winter, one or extent
tain two determined by the orographic system, and
every season, and occasionally more. Sawingby outtheof
distribution of mountains and plains described
the ice in the following June, and pressing northward 'From tle Rio .Newas.

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APRIL 10, 1885.] SCIENCE.

in Scienice, No. 112. They are, however, still more the south tile Atlantic-Parani dlivide is formed by
dependent on the general structure of South America;the culminating ridges of the southern part of the
since almost all of the great Brazilian rivers belong toSerra do Mar; in the central portion the ParaniS-Sao
hydrographic systems which interest other parts of Francisco divide is formed by the Serra da Canastra,
the continent outside of the Brazilian plateau. or Matta da Corda, in western Minas, and by the
South America is made up of three great masses transverse ridges which unite this chain with the Man-
of highlands, in great part mountainous, more or lesstiqueira branch of the Serra do Mar, and with the
completely separated by depressed areas, in which mountains of Goyaz; in the northern portion of the
flow the great rivers Ainazonas, Orinoco, and Para- great watershed the divide is forme(d by the exten-
guay; the latter, rather than the Parand, being taken sive ridge, which, branching off from the Goyaz Moun-
as the dominant feature of the La Plata system.1 tains, accompanies all the course of the Tocantins, -
These masses of highlands are, the long and narrow a ridge whose true orographic character is, as stated
Andean plateau, the Brazilian plateau, and the pla- in a previous article, very imperfectly known.
teau of Guiana. The Andean plateau, being very The secondary watershed, which divides the waters
near the Pacific coast, throws nearly all the drainageof the Amazonas from those of the La Plata system,
of the continent eastwards to the Atlantic; while theis well defined and regular in the part between the
plateaus of Brazil and Guiana force the waters to Araguaya-Tocantins and the Paranti, being formed
flow northward to the Caribbean Sea, southward to by the mountains of southern Goyaz, which extend
the South Atlantic, or eastward through the central from south-west to north-east; but farther west, be-
basin, or great Amazonian depression which sepa- tween the Paraguay on the one side, and the Xingu,
rates them. Thus the Paraguay has a southerly Tapaj6s, and Guapore, of the Amazonian system,
course in the centre of the great depression between on the other, the divide is near the irregular jagged
the Andean highlands and those of Brazil, receiving margin of the Amazonian tableland, and is not
a considerable part of the drainage of both; the Ori- marked by any notable elevation of the surface; and
noco bears the same relation to the highlands of the the passage from one system to the other is compara-
Andes and of Guiana, which give a northerly course tively easy. Thus in the detached Serra do Aguapehy,
to the drainage; while the vaster Amazonas has rela- which seems to be an outlier of the southern margin
tions with all three of the continental plateaus, ris-of the tableland, rise the Rio Alegre - one of the head
ing in the Andes, and flowing between the highlands waters of the Guaporde- and the Aguapehy, which,
of Brazil and of Guiana, receiving tribute from both through the Jauru, discharges into the Paraguay. In
of them, while by means of its great tributaries,the thelower lands at the base of the serra, and after
Madeira, Rio Negro, and others above them, it in- both these streams have become navigable for small
cludes in its basin a considerable portion of the great
craft, they flow for a certain distance near together;
depression between the Andes and the two detached and the intervening land affords two practicable
eastern plateaus of the continent. portages of the extension of S,64(0 metres an(l 11,708
With few exceptions, all the great rivers of Soutl metres respectively, over which boats have been
America belong to one or the other of these basins, passed from the waters of the Paraguay to those of
which may be called continental, because they per- the Amazonas, or vice versa. Iln 1773 an attempt
tain to more than one of the great component parts was made to open a canal across the shortest of these
of the continent. The other rivers belong to one or portages, wliich, like the Cassiqliari, should serve
another of the three plateaus; and of these, those of two great basins, and afford uninterrupted
to unite
Brazil are the largest and most important, because fluvial communication from the mouth of the La
the Braziliat plateau is larger than that of Guiana, Plata to that of the Orinoco. The attempt was, how-
and better watered than the part of the Andes that ever, abandoned; and accurate levelling will probably
drains into the central depressions. Considering the show that the project is impracticable. There are
Uruguay as belonging to the La Plata system, the also two practicable portages between the affluents
exclusively Brazilian rivers (in a geographical sense)of the upper Tapaj6s and the Cuyaba, a tributary of
are those that flow from the eastern watershed of the Paraguay. One of these is only 1,285 metres
the plateau directly to the Atlantic. If, however, wide; and cainoes with cargoes of Amazonian products
not only those that have their course in the country, have frequently been transported to the waters of
but also those that commiience or terminiate in it, are the Paraguay. As in this region the Tapaj6s flows
consideredas Brazilianl, the rivers group themselves at a much higher level than the Cuyabl (at least, ill
naturally into three great divisions; viz., those that its navigable portion), the difference of level to be
flow directly to the Atlantic, and those that form part overcome is probably much greater than ill the case
of the Amazonian and Platine systems. of the Alegre and Aguapehy.
The great watershed of the empire, that whicl In consequence of the disposition of the hlighlands
separates the indirect from the direct Atlantic drain-and1 lowlands above indicated, there is a great differ-
age, is determined by the orographic features alreadyence between the rivers of these two divisions, which
described. It does not, however, follow continu- is of capital importance witll reference to the inter-
ously the culminatingr orographic lines, but rather nal communications of the empire. The Amazonas
passes from one to another of these lines by meansand Paraguay, being: pre-eminently rivers of the de-
of the transverse ridges which unite them. Thus in pressions (the first descends to a level of less than 10)
1 See the map on p. 274. metres very near to the foot of tile Andes, and the

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 298 SCII j N CE. [VOL. V., No. 114.

latter flows at an elevation of only 123 metres at The paranamirins would in this h
Cuyaba near its source), afford uninterrupted naviga-sent the marine channels of the muddy bottom of
tion for almost their entire course. The tributaries the estuary. It is certain that the lower portion
of these two rivers, and the other Brazilian rivers of theinAmazonas valley still presents so much of
general, are, however, plateau streams, and have thetwo
character of an estuary, that a question has
navigable portions,- one on the upper streamarisen on theamong geographers as to whether the Tocan-
plateau; and the other in the depression, or coast tins should be considered as a tributary, or an inde-
border region. The difference of level between thesependent river. The fact that it receives a considerable
two portions is one or more hundred metres, and thequantity of water from the Amazonas through vari-
descent has to be accomplished by a series of cata- ous furos decides the question of its being a tribu-
racts situated at a relatively short distance above tary, since the Amazonas contributes much more
the mouth of the river. Of these, the most notable water than the Tocantins to the so-called Para River,
are the Paulo Affonso cataract on the Sao Francisco, which is only the southern branch of the great Ama-
and the Sete Quedas (' seven falls') on the Parana. zonian estuary.
The upper tributaries of the Amazonas, between the Attention has often been called to the curious fact,
foot of the Andes and the Rio Negro on the north, that, unlike most large sediment-loaded rivers, the
and the Madeira on the south, are exceptions to this Amazonas has no delta. The reason appears to be,
rule; since they descend from the plateau on which that its lower course is still in a transition state be-
they rise in their upper courses, and afford long lines tween the estuary and fluvial conditions; and the
of navigation. They thus reveal the interesting fact delta is not to be looked for at what is generally con-
that a vast area of the almost unknown upper Ama- sidered as the mouth of the river, but higher up at
zonian region is at a much lower level than the adja- the head of the estuary. In this case the network
cent plateaus. Of the rivers that flow directly to of canals between the mouth of the Xingdi and the
the Atlantic, those of the province of Maranhio and western end of the island of Maraj6 may be consid-
the Parnahyba, in Piauhy, offer the greatest facilities ered as the true delta.
for navigation; because they rise at a lower level than In a certain sense, the La Plata basin is a triple
the rivers to the southward, and effect their descentone, since a slight change of level, which should take
to the sea-level by a gradual slope distributed along the head of the estuary to the mouth of the Parana,
the whole course, instead of being concentrated inwould effect the separation of the Paraguay, Parana,
one or more grand series of rapids. and Uruguay as three distinct basins. Although
The Amazonas and Paraguay present peculiar fea- smaller than the Parana, the Paraguay should be
tures in the very extensive alluvial plains that borderconsidered as the main stream on account of its rela-
the main river and the lower courses of their tribu- tions with the elevated portions of the continent to
taries, and in the great number of arnastomosing lat- the east and west. The Parana, as already stated,
eral channels that cut these plains and put the main is essentially a highland river. Its tributaries flow
river in communication with the tributaries, often into at it before it enters the depression by the great
long distances above the junction, and these last with cataract of Sete Quedas. The only exception is the
each other. These canals are particularly notable in Iguassu, which has its great cataract of Santa Maria
the case of the Amazonas, where they are called para- close to the junction. A peculiarity of the Parana is
namirins, or furos; I and it is said that a boat may that the eastern margin of its basin is so close to the
traverse almost the entire length of the Amazonas Atlantic, that one of its tributaries, the Tiete, may
valley without entering the main stream. The for- be said to rise in sight of the sea. Another peculiar
mation of these canals is to be attributed in part to feature is the tendency of its eastern tributaries,
the formation of alluvial islands that are constantly especially myarked in the case of the Tiete, to flow in
being created by the sediment-loaded waters of the a north-westerly direction, as if they were seeking
great river. The number and character of many of the source, rather than the mouth, of the main river.
them, and especially of the furos, seem, however, to This indicates a general north-westerly slope in this
indicate a more general cause, and suggest the idea, part of the plateau.
that, since a relatively slight depression of the sur- A few peculiarities in the principal rivers of the
face would transform the river-valley into an estuary, direct Atlantic drainage system, which indicate inter-
it may reasonably be supposed that at some time a esting points in the topographical structure of the
correspondingly slight elevation has transformed an country, may be mentioned here. Sucli a point is the
estuary into a river-valley. The long distance to general parallelism of the Sao Francisco to the coast-
which the influence of the tide (it is sensible at Oby- line in the greater part of its course, due to the river
dos five hundred miles above the mouth of the Ama- being confined behind the Serra do Espinhaco, which,
zonas) is felt, gives an air of probability to this terminating to the northward, finally permits the river
hypothesis. In this case the present tributaries to escape, and direct its course toward the sea, making
would have been independent rivers, and would nat- a right angle to its former course. The same phenom-
urally have had deltas, the canals of which would inenon is presented in a still more interesting manner
part become closed, and in part be transformed into by the Parahyba, which exhibits a double parallelism,
furos, when the estuary was changed into a river. the river making a U-curve in the upper part of its
1 The former are canals that return to the same river from
course, and, after a course of about two hundred
miles,
which they parted; the latter, those that unite two distinct passing
rivers. close by its source. This is due to a

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APrIL 10, 1885.] SCIENCE. 299

subordinate
subordinatemembermember
of the Serra do
ofMar
the
system
Serra
(the interesting
do Mar anorthite
systemrock.
(theTo the acid erup-
Serra
Serra da Bocaina,
da Bocaina,
or Quebra Cangalha),
or Quebra which, Cangalha),
beingtives he has which,
made a morebeing
notable contribution
intercalated between the maritime range and the Serra
in determining not only the presence, which
da Mantiqueira, impels the river to the south, until,
escaping around the end of this barrier, it encounters
was partially known before, but the important
development of quartzless porphyries, quartz-
another in the Mantiqueira, which forces it north-
ward until it finds a passage across the Serra do Mar, iferous porphyries, felsites, augite syenites,
and escapes to the sea. The Iguape, or Ribeira, in granitells, and granites. He shows that these
southern Sao Paulo, with its northern tributary the are, at the same time, members of the original
Juquia, reveals the same fact of the splitting-up of eruptives, and chief contributors to the detri-
the maritime range into distinct ridges. tal beds, especially the conglomerates. But
0. A. DERBY. more completely new and theoretically impor-
tant is the recognition of a class of interme-
IRVING ON THE COPPER-BEARING
diate rocks (silica from fifty-two to sixty per
ROCKS OF LAKE SUPERIOR. cent) which constitute phases of the orthoclase,
uralitic, and hornblende gabbros, and of the
IN his opening chapter, Professor Irving diabases, diabase porphyries, and their amyg-
gives a succinct history of the earlier investi- daloidal forms. The detrital rocks are con-
gations of the copper-bearing rocks of Lake glomerates and sandstones, with shaly phases.
Superior, a clear exposition of the views that They are chiefly derived from the acid erup-
have been held respecting them, and a full tives, though where closely associated with
bibliography of his subject. The discussion basic rocks, a large element is derived from
proper is introduced by a sketch of the extent these. In some parts a notable contribution
and leading characters of the formation, illus- has been made by the older crystalline rocks.
trated by an excellent map. This is the first The lithological discussions are critical, and
really synoptical view of the series, in any evince a familiarity with the latest phases of
thing like its regional entirety, that has been this rapidly developing branch of study. They
presented. embrace a hundred and eighteen pages.
Instead of a mere local phase of some well- Following this are nearly two hundred pages
known geological horizon, it is described as a devoted to the stratigraphy of the series. The
unique formation of consistent characters and author maintains with justness, that the igneous
enormous thickness, stretching out to an ascer- beds, being overflow sheets, are fully amenable
tained length of five hundred miles, with a to the common laws of stratigraphy; and his
width of a hundred miles, and an area, ex- discussion is notably free from the license of
cluding the Nipigon extension in Canada, of eruptive geology. He brings together for the
forty-one thousand square miles, -nearly two- first time, from his own and others' observa-
thirds the size of New England. "Through- tions, specific descriptions of the formation
out this wide extent, though local peculiarities from all sides of the Lake-Superior basin. It
are to be noted, the general characteristics of is to be hoped that in this he inaugurates a new
the group are wonderfully constant." It con- era in the discussion of Lake-Superior geology,
sists of an enormous series of eruptive sheets, in which the study of its problems shall be
-- lava overflows in the main, - among which cosmopolitan, in distinction from that narrow
are intercalated beds of sandstones and con- provincialism or that distant unfamiliarity
glomerates, and over which lies a great thick- which has so largely vexed their past history.
Professor Irving's descriptions necessarily fall
ness (fifteen thousand feet) of detrital material,
making a total pile of forty thousand feet. much short of full completeness; but they con-
A careful description of these rocks next stitute a great advance in the endeavor to give,
follows, illustrated by very fine microscopic by precise descriptions, maps, and sections,
sections, and conveniently summarized in an approximately accurate conception of the
tables. The studies of Professor Irving do entire formation, so far as displayed in the
not add greatly to the kinds of basic rock Superior region. Completeness will only be
previously described by Professor Pumpelly approached
in when it is possible to extend over
the reports of Michigan and Wisconsin; viz., the whole region such excellent detail work as
diabases, malaphyrs, and gabbros. He has, that of Pumpelly and Marvine in Michigan,
however, amplified the varieties and the geo- and the author himself in Wisconsin.
graphical distribution of these, and added an The eighth chapter of the monograph is de-
voted to the relations of the Keweenaw series
M3onographs of the U.S. geological survey. Vol. v. The cop- to the associated formations, and traverses the
per-bearing rock's of Lake Superior. By ROLAND) DUER IRVING.
Washington, Government, 1883. 16+464 p., 29 pl., 37 figs. 4?. ground which has been most contested in Lake-

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