GEOGRAPHY FORM TWO WORK
- They are also called endogenic or endogenetic processes.
- These are processesoperating in the interior of the earth resulting in e
landforms.
- They include folding, faulting and vulcanicity.
- Formation of landforms by internal land forming processe
(i) Nature of rocks 1.e. soft rocks are more elastic henc ms landforms
compared to hard/rigid rocks.
(ii) Age of rocks i.e. young rocks are elastic andforms compared
to old rocks.
(111)
Typeof earth movement involv vertical earthmovement
forms different landforms.
(iv) The intensity and scale of forces in le strong tectonic forces easily
forms different landforms co tectonic forces.
Tensional forces
e Compressional forces
e Shear forces
e Gravitational forces
Types of Earth Movements —kcse2007
ntal earth movement
b) Vertical earth movement
(a) Horizontal earth movements
- These movements are also known as lateral/orogenic earth movements.
- They are displacement of the earth’s crustal rocks along a horizontal plane due to tectonic
forces causing rocks to stretch, shorten or shear.
1/Page
, Causes of Horizontal Earth movements.
(i) crust.
Tensional forces which pull the crustal rocks apart causing stretching of the earth
(ii) Compressional forces which push crustal rocks tow each other ing them to
be compressed/shorten.
2|Page
, Effects of horizontal Earth movements
(i) They cause strain and stretching of crustal rocks due to tensional forces which
cause formation of cracks/faults.
(ii) They cause squeezing and shortening of crustal rocks due to compressional
forces which also cause formation of faults.
(iii) They cause crustal rocks to shear by slipping past each other or by dividing
into layers which is causedby shearforces.
Resultant features of Horizontal earth Movements.
Y Faults
Rift valleys
Escarpments
v Basins
Y Tilt blocks
Y Block mountains
(b) Vertical earth movements
- These are also known as epeirogeni
- They are displacement of crustal roc s of the earth either towards the
earth surfaces or towards its c
Reed) Pete
Go
, (111)
7ilting- crustal rocks tilt if forcesof unequalmagnitudeact on them ie
a
Effects of vertical earth movements.
(i) They cause subsiding/sinking/down warping or pulling downwards.
(ii) They cause uplifting/upwarping or pushing of crusta ware
(iii) Theycause tilting of crustal rocks or shearing in vertical di ue to greater uplift
on one side.
Resultant
Tilt blocks
Rift valleys
1. Magma Movemer within the earth’s crust-kcse 2017
- Molten rock (me o orcedto intrudeinto the earth’scrustthrough
a line of
weakness caus x displacement.
rocks areforced to move/give way to intruding magma as their place is taken
ruding magma.
el
- They are also called endogenic or endogenetic processes.
- These are processesoperating in the interior of the earth resulting in e
landforms.
- They include folding, faulting and vulcanicity.
- Formation of landforms by internal land forming processe
(i) Nature of rocks 1.e. soft rocks are more elastic henc ms landforms
compared to hard/rigid rocks.
(ii) Age of rocks i.e. young rocks are elastic andforms compared
to old rocks.
(111)
Typeof earth movement involv vertical earthmovement
forms different landforms.
(iv) The intensity and scale of forces in le strong tectonic forces easily
forms different landforms co tectonic forces.
Tensional forces
e Compressional forces
e Shear forces
e Gravitational forces
Types of Earth Movements —kcse2007
ntal earth movement
b) Vertical earth movement
(a) Horizontal earth movements
- These movements are also known as lateral/orogenic earth movements.
- They are displacement of the earth’s crustal rocks along a horizontal plane due to tectonic
forces causing rocks to stretch, shorten or shear.
1/Page
, Causes of Horizontal Earth movements.
(i) crust.
Tensional forces which pull the crustal rocks apart causing stretching of the earth
(ii) Compressional forces which push crustal rocks tow each other ing them to
be compressed/shorten.
2|Page
, Effects of horizontal Earth movements
(i) They cause strain and stretching of crustal rocks due to tensional forces which
cause formation of cracks/faults.
(ii) They cause squeezing and shortening of crustal rocks due to compressional
forces which also cause formation of faults.
(iii) They cause crustal rocks to shear by slipping past each other or by dividing
into layers which is causedby shearforces.
Resultant features of Horizontal earth Movements.
Y Faults
Rift valleys
Escarpments
v Basins
Y Tilt blocks
Y Block mountains
(b) Vertical earth movements
- These are also known as epeirogeni
- They are displacement of crustal roc s of the earth either towards the
earth surfaces or towards its c
Reed) Pete
Go
, (111)
7ilting- crustal rocks tilt if forcesof unequalmagnitudeact on them ie
a
Effects of vertical earth movements.
(i) They cause subsiding/sinking/down warping or pulling downwards.
(ii) They cause uplifting/upwarping or pushing of crusta ware
(iii) Theycause tilting of crustal rocks or shearing in vertical di ue to greater uplift
on one side.
Resultant
Tilt blocks
Rift valleys
1. Magma Movemer within the earth’s crust-kcse 2017
- Molten rock (me o orcedto intrudeinto the earth’scrustthrough
a line of
weakness caus x displacement.
rocks areforced to move/give way to intruding magma as their place is taken
ruding magma.
el
