MANGU PREMOCK EXAMINATIONS

GEOGRAPHY
PAPER 1 MARKING SCHEME

MARKING SCHEME
SECTION A
1. The diagram below shows some weather station instruments.

(a) Identify the instruments marked K, L and M. (3 marks)

K- Anemometer
L– Sunshine recorder
M– Rain gauge

(b) Give two modern methods of weather forecasting. (2 marks)

Use of artificial satellites.
Use of a radiosonde.
Use of computers.
Use of an aero sound.
Use of weather radars.

2. (a) Give the two main movements of the earth. (2 marks)

Rotation of the earth

Revolution of the earth
 (b) State three reasons why the interior of the earth is very hot. (3 marks)

The original heat at formation is still being retained.

Due to the weight of overlying materials.
Due to the breakdown of radioactive elements.

3. The diagram below show the occurrence of an earthquake

the parts marked A, B and C (3marks)

A–Seismic focus
B– Epicentre
C– Shock waves

wo scales used to measure the magnitude of an earthquake.(2 marks) Richter scale

Moment magnitude scale
4. State five characteristics of coniferous forests. (5 marks)

Tree species are softwoods

Most tree species are evergreen.
The trees have a big portion of stem compared to the leaves.
Trees have a conical shape to allow snow to slide off easily.
Trees have needle like leaves.
Trees occur in big pure stands.
Trees have a thick bark which is waxy to protect them from winter cold.
The forest floor has very little or no undergrowth due to long winters.
Trees have wide shallow roots to utilize moisture from the top soil.
Trees are tall with flexible trunks to prevent breaking during strong winds.
5. (a) What is soil catena? (2 marks) Soil catena refers to the sequence variation of soil
derived from the same parent material down a slope from top to bottom.
 (b) State three factors that influence soil colour. (3 marks)

The chemical composition of the soil particles

The amount of organic matter present in the soil.
The type of parent material from which the soil has developed.
The drainage of the area in which the soil is found.

SECTION B

6. Study the map of Oyugis (1:50, 000, sheet 130/1) provided and use it to answer the following
questions.

(a) (i) Identify two relief features at grid square7342. (2 marks)

Hills
Steep slope
A river valley
A pass

)Measure the distance of road E 212 from its junction with road C 18 to the junction at grid square
7542. Give your answer in kilometres. (2 marks)

7.9 km (accept 7.8 km or 8.0 km)

i)Determine the six figure grid reference of Kitweru School. (2 marks)

748174

(b) (i) What is the vertical interval of the map? (1 mark)

50 feet

(ii) Determine the bearing of a jaggery factory at grid reference 788237 from a church at
grid reference 806188. (2 marks)

0 0 0
340 (accept 339 or 341 )

(c)(i) Draw a square 10cm by 10cm to represent the region east of easting 85 from northing 30
to northing 40. On the square, mark and name.

Kodera forest.

Oriang’ hill
A district boundary.
All weather road-bound surface.
A seasonal swamp (6 marks)

(ii) What is the scale of the sketch that you have drawn? (1 mark)

1:100,000

(d) (i) Citing evidence from the map, identify four crops grown in the area covered by the
map. (4 marks)

Crop - evidence
Coffee - presence of coffee factories
Sugarcane- presence of a jaggery factory and sugar research station
Cotton - presence of cotton stores
Maize - presence of flour mills
(ii) Describe the distribution of settlement in the area covered by the map.
(5 marks)

There are more settlements on the eastern part of the map than in other parts.
There are clusters of settlements at shopping centres or markets
Kodera forest has no settlements
Areas with hills have no settlements
Regions with river valleys have very few or no settlements
There are no settlements within the seasonal swamp at mwakibagendi
Some settlements occur along main track motorable roads forming linear settlement pattern.
The western parts have moderately distributed settlements

7. (a) (i) What is a mineral? (2 marks)

A mineral is a naturally occurring inorganic crystalline substance with a definite chemical

composition and physical properties.

OR

A mineral is an inorganic substance with a definite chemical composition occurring naturally at or

beneath the earth surface.

(ii) Give three ways used to classify rocks. (3 marks)

According to their mode of formation.

According to their chemical composition.
According to their age.

(b) (i) Describe how igneous rocks are formed. (5 marks)

High temperatures in the interior of the earth causes materials to be in molten form.(magma)
High pressure underneath pushes the molten magma through lines of weakness such as faults
and vents.
If the pressure is low, magma fails to reach the earth’s surface. The magma cools and solidifies
below the surface forming intrusive igneous rocks.
If the pressure acting on magma is high, the magma reaches the surface as lava.
The lava cools on the earth’s surface forming extrusive igneous rocks.
(ii)List three examples of mechanically formed sedimentary rocks. (3 marks)

Sand stone Grit Shale Mudstone Siltstone Claystone

Loess Breccia Conglomerate Boulder clay

(c) Explain three types of rock metamorphism. (6 marks)

During thermal/contact metamorphism, hot magma intrudes original crustal rocks during
vulcanicity. The hot magma may melt and recrystallize some sections of the original rock
thus altering them forming new minerals.
 During dynamic metamorphism, intense compressional pressure acting within a limited
area thus alters the structure and texture of crustal rocks. Weight materials overlying
some sedimentary rocks may alter the structure of bottom layers.

Regional metamorphism occurs during fold mountain formation. Intense compressional

force/pressure and heat act on sedimentary rocks over a wide area altering both the
structure and chemical composition of the rocks.

(c) Suppose you were to carry out a field study on rocks in the area surrounding your school
(i) State three characteristics that you would look for while identifying
different rock types (3marks)
The hardness of the rocks
The density of the rocks
Texture of the rocks
Colour of different rocks
Lustre of the minerals farming the rock
Shape of the rock crystals
(ii) State three follow up activities for the field study (3marks)
Writing a report in essay form
Displaying photographs on rocks taken from the field
Displaying labelled samples
Laboratory testing of the mineral composition of some rocks collected
Discussing the findings in groups
Giving a lecture to the students who never went.

8. (a) (i) Differentiate between faulting and folding. (2 marks) Folding is the process through
which young sedimentary rocks bend upwards or downwards due to compressional forces
whereas faulting is the process through which crustal rocks fracture due to tectonic forces such
as tension, compression or shear.

(ii) Name five features formed as a result of faulting. (5 marks)

Rift valleys
Fault blocks (Block mountains and Horsts)
Tilt blocks
Escarpments/fault scarps
Fault steps

(b) The world map below shows the location of some fold mountains. Use it to answer question
(a)(i)
 (i) Identify the fold mountains marked W, X, Y and Z (4 marks)
W– Rockies
X– Alps
Y– Andes Z – Ural
(ii) Citing relevant examples, explain how Fold Mountains were formed according to the plate
tectonics theory. (6 marks)
Fold Mountains are formed when two tectonic plates meet along compressional tectonic
plate boundaries
When an oceanic plate meets a continental plate the edges of the sediments and materials at
the margins into fold mountains e.g. Andes and Rockies
Fold Mountains are also formed when two continental plates meet squeezing the materials in
between into Fold Mountains e.g. Himalayas Atlas and Alps. (c)Explain the effects of Fold
Mountains on the following

Transport. (2 marks)
Fold mountain scenery acts as a barrier to easy construction of roads, railways and pipelines thus
making it difficult to access some regions due to ruggedness.
)Agriculture. (2 marks)
Leeward slopes of some fold mountain ranges receive dry winds leading to arid conditions. This
discourages crop farming but favours ranching and transhumance
Windward slopes of most fold mountains receive high orographic rainfall which supports crop
farming
i)Tourism. (2 marks)
Fold mountain scenery and snow-capped slopes are important tourist attractions with some
slopes favouring winter sports such as skiing and ice skating, e.g. Swiss Alps
v)Mining. (2 marks)
Along some slopes of some Fold Mountains, valuable minerals were exposed thus are exploited
for various economic uses e.g. copper and tin along the Andes slopes in Bolivia and Chile.
9. (a) Give three examples of West coast deserts. (3 marks)

Namib
Atacama
Californian
The Great Sandy Desert of Australia

(b) (i) Apart from rock pedestals, name four other features formed due to wind erosion in arid
regions. (4 marks)

Zeugen
Yardangs
Mushroom block
Deflation hollows and oases
Ventifacts

(ii) With the aid of well labelled diagrams, describe how a rock pedestal is formed. (7 marks)

Initially, there existed an outcrop rock mass with horizontal and alternating layers of hard and soft
rocks.
The heterogeneous rock lie on the path of prevailing wind on a desert.
The rock was weakened by both weathering and wind abrasion.
The soft layers are eroded faster thus forming hollows.
The hard/resistant layers are worn out slowly hence bulge.
Abrasion is greater at the lower part of the outcrop rock thus greater undercutting. With time, this
resulted in an irregular rock pillar with a narrow base called a rock pedestal.

[Diagrams 2 marks]
[Description 5 marks]

(c) Explain four factors that influence the rate of wind transport. (8 marks)

The strength and the speed of the wind. A strong wind transports heavier and more materials
 than a weak wind.
Presence of obstacles such as outcrop rocks and vegetation reduce the wind speed hence
reducing its capacity to transport materials.
Nature of the materials transported. Light particles such as dust are transported to great
distances while heavier sand and pebbles over short distances.
Wind transport is effective during a hot and dry season. Weather changes such as torrential
rain washes air borne particles to the ground.
(d) State three negative influence of desert features. (3 marks)
Advancing sand dunes can be barriers across transport lines such as roads. Spreading sand
dunes encroach onto productive land hence desertification.
Flash floods from torrential rains in deserts deposit materials that block roads.
Excess surface run off flowing in wadis may sweep away and drown people
10. (a) (i) What is a lake? (2marks)
A lake is a mass of water which occupies a depression/basin/hollow on the surface of the
earth.
(ii) Give three processes that lead to formation of Lakes. (3marks) Through earth
movements.
Through vulcanicity.
Through erosion.
Through deposition.
Through mass movement.
Through weathering by solution.
Through human activities.
(b) Describe how Lake Victoria was formed (6marks)
Internal land forming processes caused vertical earth movements which resulted in down warping
of a huge region.
Down warping led to the formation of a huge depression/basin.
Uplifting of landmasses around the depression during the formation of the Mau Ranges and the
Ruwenzori altered the drainage of the area.
Some rivers from Kenya which flowed westwards were cut off and diverted into the depression.
Some rivers in Uganda such as Katonga, Kafu and Kagera were reversed to flow into the
depression.
Deposition of water into the depression caused further down warping.
The mass of water which accumulated formed Lake Victoria.
)Explain three factors why some Lakes in the Rift Valley in Kenya are saline.
(6marks)
Some rivers and surface runoff flowing over volcanic rocks empty salt solutions in some lakes
thus increasing salinity.
 Some lakes lack surface outlets in form of rivers which lead to accumulation of salts.
Some lake beds are made of rocks rich in soluble salts where the lake water directly dissolves
some salts thus increasing salinity.
Some lakes are fed by springs rich in salty water which contributes to salinity.
Some lakes are located in high temperature regions with high evaporation rates thus
accumulation of salts.
)Explain four ways in which lakes influence the climate of the surrounding areas.
(8marks)
Large lakes contribute large quantities of moisture which aids in the formation of convectional
rainfall.
Lakes increase the absolute humidity of the surrounding area by adding extra moisture through
evaporation.
Lakes facilitate the development of land and lake breezes through creation of pressure
differences between water surface and the land surface.
Air currents from lakes lower the temperature of the surrounding regions during the hot/summer
season.
During winter, lake breezes may bring a warming effect to adjacent regions e.g. The Great lakes of
North America.
Land and lake breezes may strengthen or reverse the pattern of prevailing winds over adjacent
regions.