1. FAULTING
• A fault is a break, crack or a
fracture in the Earths crust
• produced by vertical and lateral
movements within the earth’s
crust.
• Faulting is one of the internal land
form building process which
shapes the earth’s surface.
• It is caused by earth movements,
which create forces of tension and
compression that are either lateral
or vertical.
• If forces of tension and
compression are created by earth
movements the rocks of the earth
crust may fracture or crack.
• thus the faults are formed .
• The line along which rocks have
fractured is called a fault.

2. Types of Faults
• Normal fault
• Reverse fault
• Tear/Shear fault
• Thrust fault
• Anticlinal fault

3.  Formed when rocks are subjected to
tensional forces .
 Normal faults develops.
 One block of land slides downwards in relation
to the other.
 These types of faults are common in the East
African section of the Great Rift valley.
Normal Fault
Down throw
upthrow

4. Reverse faults
• These are also known
as thrust faults .
• caused by the forces
of compression.
• when the strata or
layers are compressed
or pressed ,the rocks
will crack and faults
will be formed.
• One block of rocks
may override another
to form a block .
• mountain or a horst.
• Such faults are
common in western
Uganda.
• The Ruwenzori
mountain is an
example of a block
mountain formed by
thrust faults
Down throw Up throw

5. Tear faults
When lateral
movement is taking
place particularly
during an earthquake,
tear faults may occur.
Tear faults are also
known as wrench or
transform faults. If a
tear fault occurs
across the course of a
river, then the river’s
course may be slightly
offset.

6. FEATURES FORMED
(PRODUCED) AS A RESULT OF
FAULTING
Faulting has produced a
variety of physical
features over the
surface of the earth.
Among the most
remarkable features are;
 Block mountains
 Rift Valleys
 Tilt blocks
 Escarpments/Fault
scarp

7. A BLOCK MOUNTAIN
A block mountain is also
known as a Horst. It is formed
when the middle block which
is bounded by more or less
parallel faults is made to rise
or is uplifted by the
compressional forces. The
best example of a block
mountain in East Africa is
mount. Ruwenzori ranges,
also known as the mountains
of the moon. Others include
Mathews ranges and Nyiru
Ndoto in Northern Kenya.
Ablockmountainisalsoknownasa Horst.It

8. Rift valleys or grabens

9. Tilt Blocks
Tilt blocks are formed
when one side of the
middle block is
uplifted higher than
the other side. The
top of the middle
block will not be flat
but will be tilted. E.g.
west Kenya tilt block,
which rises to about
1900 meters towards
lake Victoria.

10. Escarpments
Escarpments are steep cliff-like slopes. Escarpments
are said to have been formed during the formation of
the rift valleys.
Some escarpments are steep and may extend several
hundreds of kilometers . When escarpments are
eroded, they become fault scarps.
Examples of such escarpments in East Africa include:
 Nandi(Kenya)
 Butiaba (Uganda)
 Elgeyo Marakwet (Kenya)
 Kikuyu (Kenya)
 Mau (Kenya)
 Lake Manyara (Tanzania)
 Nyando (Kenya)
 Keiyo (Kenya)
 Nyandarua or Aberdares (Kenya)
 Chuya (Tanzania.)

11. Problems faced by the people living in
the Rift valley areas of East Africa
High temperatures lead to shortage of water.
Earthquakes (tremors) which destroy property
Little rainfall or drought in the Rain shadow
areas
Poor means of transport and communication
because of the steep escarpments

12. Importance of faulting
• Faulting has resulted into the formation of high mountains in East Africa. For example the Ruwenzori in
western Uganda, the southern highlands and the Usambara mountains in Tanzania and the Mathew ranges
in Kenya. These are the most productive areas, where both cash crops and subsistence crops are grown.
• These highlands receive abundant and reliable rainfall.
• Rift valley lakes for example L. Tanganyika, lake Turkana, lake Naivasha and lake Baringo are fishing grounds.
• Some of these lakes have fresh water which can be used for irrigation and also for domestic purposes and
industrial use.
• L.Magadi contains vast deposits of soda ash, which is one of the most important minerals in Kenya.
• Faulting presents an impressive scenery which can be used for tourism. For example L.Nakuru has millions of
colorful flamingos and other birds.
• Some highlands have been made into National parks and game reserves e.g. the slopes of the Nyandarua
and Ruwenzori mountains . These parks attract many tourists.
• Faulting can also cause the formation of waterfalls such as the Karuma falls, Murchison falls.
• Problems caused by faulting
• Escarpments and mountains hinder transport development.
• Rift valleys are very hot and only suitable for grazing because they are in the rain shadow unless irrigation is
practiced as with the case of mubuku.
• There is severe soil erosion and mass wasting on the step slopes which result in the destruction of soil
surface, crops and at times people's property. For example Ruwenzori mountains.
• It is difficult to settle on the steep areas on the rift valley escarpments.

13. RIFT VALLEYS
A rift valley is an elongated trough bound by two in-
facing escarpments.
Rift valleys are long, narrow depressions on the earth
surface bounded by more or less parallel faults. A rift
valley is also known as a graven.
Rift valleys are thought to have been developed either
from the action of tensional forces in the crust or from
the action of compressional forces.
The East Africa rift valley system extends southwards
from the Red sea. Through Ethiopia and East Africa to
Malawi.
The east Africa rift valley covers a distance of
approximately 5,600km .it is divided into two
branches that is, the western rift valley and the
eastern rift valley.
The Western branch stretches from lake Albert in
Uganda to lake Malawi. The eastern branch stretches
from lake Turkana in northern Kenya to lake Malawi.
The width of the rift valley varies from place to place.
The average width is between 50km and 60km.
On the floor of the rift valley there are a number of rift
lakes and volcanic craters such as Longonot crater and
Menengai craters.

14. Origin of the rift valleys
• A number of theories have been put forward to
explain the origin of rift valleys. However, two
have remained popular thus, there the two
theories which attempt to explain the origin of
rift valleys. One relies on the forces of tension
and the other on the forces of compression. Both
theories depend on upward swells, along the
sides of which faults develop.

15. Origin of the rift valleys
Theory 1: Tensional forces Theory 2. Compressional forces
After subsidence a depression with steep fault scarp sides i.e. a rift valley is formed. It is trapped in
position by later pressure.
Theory 1: Tensional forces
a) Tension forces act on the
layers of rock
b) Gradually two parallel faults appear
and the central block begins to subside
(sink).
c) Land in between sinks in forming a rift valley. The
land on either sides stays in place.
a) Layers of rocks are subjected to
compressional forces.
b) Faults develop and the outer blocks move
upwards (Reverse faults are formed).
c) Central block stays in place and a rift valley is
formed.

16. RIFT VALLEY LAKES
• These have been formed
on the floor of the rift
valley and they vary in
size, depth and salinity.
Examples of the salty
lakes are Natron, and
Magadi. The rift valley
has several in land water
basins which contain
lakes.
Rift valley lakes of East Africa
i.e.
• Kenya
• Uganda
• Tanzania include:
• L. Turkana
• L. Tanganyika
• L. Baringo
• L. Edward
• L .Rukwa
• L. Nakuru
• L. George.
• L. Natron
• L .Elmentaita
• L .Eyasi
• L. Naivasha
• L. Manyara.
• L. Albert
• L. Magadi

17. FAULTED AREAS IN EAST AFRICA
• There are faulted areas in east Africa outside
the rift valley such as:
• Kavirondo rift at Kisumu.
• Northern face of which is the Nandi scarp
• Usambara mountains have fault scarps

18. Benefits of the Rift valley to the people
of East Africa
• The beautiful scenery attracts tourists
• Lakes in the Rift valley provide fish. For example L . Tanganyika, L.
Albert etc.
• Rift valley lakes provide water for domestic and agricultural use
• Lakes help in navigation (water transport).
• Forests on the slopes are sources of timber
• Gentle slopes are used for crop farming and settlement due to
fertile soils
• Rift valley lakes are used for mining for example soda ash from L.
Magadi
• Areas of little rainfall (rain shadow) provides pasture for grazing|
• Study purposes or research
• Wildlife conservation. For example game parks in rift valley areas.