GEOGRAPHY TOPICAL QUESTIONS AND ANSWERS

Volcanic features found in the rift valley of Kenya

26/2/2021

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KCSE Geography Paper 1 2000 Section B Question 7 with Answers.

(a) Differentiate between plutonic rocks and volcanic rocks

Volcanic rocks

Form from lava
Formed in surface
Cools rapidly
Forms small crystals
Fine textured

Plutonic rocks

Form from magma
Formed deep inside the crust/intrusive/ Extrusive
Cools slowly
Forms large cry/course grained
Coarse textured

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The diagram below shows some intrusive features formed by vulcanicity. Use it to answer question (a)

24/2/2021

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KCSE Geography Paper 1 2004 Section B Question 9.

The diagram below shows some intrusive features formed by vulcanicity. Use it to answer question (a)

a) i) Name features marked X,Y, and Z

X – Laccolith
Y-Batholith
Z –Dyke

ii) Explain how a sill is formed

Rocks beneath the crust are in a semi –solid state due to high temperature and high pressure.
When pressure decreases the rocks become semi- fluid and are known as magma.
Earth movements cause vertical or horizontal cracks in the rocks
The molten rock / magma forces itself through the cracks / fissures.
When magma cools and solidifies in a horizontal crack or bedding plane it forms a feature called a sill.

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Differentiate between magma and lava.

17/2/2021

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KCSE Geography Paper 1 2008 Section B Question 7.

a) Differentiate between magma and lava.

Magma is the molten rock material which originates from the interior of the earth, cools while below the earths surface and has large crystals while lava is the molten rock materials that has reached the surface, has solidified and has small crystals.

b) The diagram below shows some intrusive volcanic features.

Name the features marked E, f and G.

E: Dyke
F: Lopolith
G: Sill

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How is a parasitic cone formed?

9/2/2021

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KCSE Geography Paper 1 2011 Section A Question 3.

The diagram below shows a composite volcano.

(a) Name the features marked P, Q and R.

Q - Lava layers
R - Dyke/slide/vent

(b) How is a parasitic cone formed?

Pressure is reduced causing the magma from the interior of the earth to fail to reach the top of the volcano.
The upper part of the main vent of the volcano is blocked.
Pressure builds up and the magma escapes through a side vent.
The successive outpourings of magma through the side vent builds alternative layers of ash and lava.
The layers of ash and lava form a conelet on the side of the composite volcano.
The coneIet is the parasitic cone.

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What is volcanicity?

4/2/2021

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KCSE Geography Paper 1 2013 Section B Question 8.

(a) What is volcanicity?

It is the process through which gaseous / liquid / molten rock / solid materials are forced into the earth’s crust and / ejected onto the surface.

(b) (i) Apart from a sill, name three other intrusive volcanic features.

Dykes/dikes
Laccolith/laccolites
Batholith/bathyliths
Lopolith
Phacolith/phacolite

(ii) Describe how the following features are formed:
I a sill;
II hot springs;
III a caldera.

I a sill;

Below the earth’s crust the rocks are at very high temperature and high pressure. If the pressure becomes less, the hot, solid rock material may become semi-fluid / Magma under high pressure enters crustal rocks.
The semi-fluid rock / magma forces itself into horizontal cracks/fissures.
The magma cools and solidities in horizontal cracks or bedding plane.
This horizontal sheet/layer of igneous rock is called a sill.

II hot springs;

Rainwater enters the crustal rocks through cracks / fissures.
The water reaches a zone of hot igneous rocks.
The water is (super) heated.
The super heated water changes into water vapour.
The vapour is under high pressure and so forces its way up heating the ground water.
The heated water under pressure flows out continuously/to form hot springs.

III A caldera.

Lava pouring out of a central vent forms a volcanic cone.
The vent may be sealed when lava solidifies in it.
The solidified plug block the gases and steam beneath from escaping.
There is pilling up of pressure below the plug.
The pressure leads to a violent eruption that blows off the top of the cone forming a depression.
The resulting large circular depression on the top of the (now lower) volcano is called caldera.

OR
A subsidence caldera

Lava pouring out of a central vent forms a volcanic cone.
The magma resevoir below the crust is left empty/has a void/cavity.
With time the weight of rocks of the volcano exerts pressure on the crustal rocks below.
The pressure/earth movements cause cracks to develop making the volcano unstable.
Over time the middle portion of the volcano subsides/collapses into the void forming a depression.
The resulting large circular depression on the top of the (now lower) volcano is called caldera.

OR
Outward collapsing

Volcanic eruption of ash and cinder/pyroclasts through a central vent forms a volcanic cone.
Several eruptions results to a high, steep and unstable volcano.
The weight of the upper materials exerts pressure on the ones beneath causing instability on the lower part.
The material at the base begin spreading outwards.
The top of the volcano collapses inwards forming a depression.
The resulting large circular depression on the top of the volcano is called caldera.

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Name two active volcanoes in Kenya.

2/2/2021

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KCSE Geography Paper 1 2014 Section A Question 2.

(a) The diagram below shows intrusive volcanic features.

Name the features marked E, F and G.

E - A sill
F - A batholith
G - A laccolith/baccolith

(b) Name two active volcanoes in Kenya.

Longonot
Teleki
Likaiyu/ Likaiu
Ol Donyo Lengai
Menengai
Suswa
Homa hills

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Differentiate between magma and lava.

30/1/2021

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KCSE Geography Paper 1 2016 Section A Question 10.

(a) Differentiate between magma and lava.

Magma is the molten rock material which originates from the interior of earth, cools while below the earth's surface (and has large crystals) while lava is the molten rock materials that has reached the surface. (Has solidified and has small crystals.

(b) The diagram below shows some intrusive volcanic features.

Name the features marked E, F, and G.

E - Dyke
F - Lapolith
G - Sill

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The diagram below represents some volcanic features. Use it to answer the questions below.

27/1/2021

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KCSE Geography Paper 1 2018 Section A Question 3.

The diagram below represents some volcanic features. Use it to answer the questions below.

Name the features marked P, Q, R and S.

P—Sill
Q- Vent
R—Batholith
S—Lopolith

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What is magma? Differentiate between a sill and a dyke.

26/1/2021

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KCSE Geography Paper 1 1998 Section A Question 2.

(a) What is magma?

It is the molten rock under the earth’s crust

(b) Differentiate between a sill and a dyke

A sill is a near horizontal/ tabular sheet of igneous rock formed from
solidified magma intruded between bedding planes, while a dyke is a shrub of intrusive rock which cuts near vertical/ discordantly across the bedding planes. ( no mark for one side only)

(c) The diagram below represents a composite volcano. Name the features marked P,Q, and R

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Using examples from East Africa, describe each of the following types of volcanoes:

18/1/2021

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(a) Using examples from East Africa, describe each of the following types of volcanoes:

(i) Active Volcano
(ii) Dormant Volcano
(b) Using a well labelled diagram, explain how each of the following features were formed:
(i) Composite Volcano
(ii) Volcanic plug
(c) Explain four negative effects of vulcanicity

EXPECTED RESPONSES

(a) (i) Active volcano

They erupted in the recent past
They show current volcanic activities.
They are likely to erupt, any time.
For examples, Ol donyo Lengai in Tanzania, Shetani, Chaimu in Kenya
Dormant volcano
Is a volcano that is not active.
Has not shown any signs of activity in the recent past.
Erupted in the last 500 years.
Is likely to erupt again, example is mount Longonot -Kenya, mount Kilimanjaro- Tanzania, Suswa, Menengai

(b) Using a well labelled diagram, explain how the following features are formed.
(i) Composite volcano

It is formed as a result of central volcanic eruptions.
Violent eruption forms a layer of ash.
The violence ceases and lava pours out forming a layer of lava on top of the ash:
Lava also escapes from the sides of the cone to form coneIet/parasitic cone.
A volcanic cone made up of ash and lava layers is built up over a long period of time as a result of many eruptions.

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State four ways in which volcanicity has influenced human activities in Kenya

12/1/2021

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State four ways in which volcanicity has influenced human activities in Kenya. (4mks)

Four ways in which volcanicity has influenced human activities in Kenya

The Volcanic rocks of the Kenya highlands have been weathered to produce fertile soil for agriculture.
Landforms resulting from activity are tourist attraction /scenic beauty e.g Mt Kenya.
Trachyte and phonolites/volcanic rocks are used for building
steams jets/gerious at Olkaria are used for generating geothermal power.
Gases associated with volcanic activities are mined in Kenya e.g CO2 at Kereita and at Esageri in Baringo
steep slopes formed through volcanic activity discourages settlement/farming/development of transport. (4mks)

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List two features resulting from extrusive volcanic activity

12/1/2021

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List two features resulting from extrusive volcanic activity.(2mks)

Two features resulting from extrusive volcanic activity

Composite volcano
Lava plateau/lava plains/tuff plateau
Caldera/crater
Ash and cinder cones
Spine/volcanic plugs
Hot spring

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