Geography ppt for csec students. very useful materials on folding and faulting

1. Chapter 9
Folding and
Faulting

2. Mountains
• Large landforms with steep slopes and heights of
above 600m
• Two types – fold mountains and block mountains
• They differ in formation, characteristics and appearance
Chapter 9: Folding and Faulting
Himalayas fold mountains

3. Folding
• Process in which rocks are bent and crumpled due to
compressional forces arising from the convergence of
two plates
• Results in the formation of fold mountains
Fold mountains
• Fold mountains are the highest mountains on the
earth’s surface
• Mount Everest is an example of a fold mountain
• It is the highest mountain in the world with a height of
8,850m and is part of the Himalayan mountain range
Chapter 9: Folding and Faulting

4. Chapter 9: Folding and Faulting
Mount Everest

5. Case study: Himalayas
• Mountain range in Asia between the Indian subcontinent
and the Tibetan Plateau
• Formed as a result of collision between the Indian
continental mass on the Indo-Australian Plate and the
Asian continental mass on the Eurasian Plate
• The two land masses were once separated by the
Tethys Sea
• When the two plates collided, the oceanic crust of the
Tethys Seas subducted beneath the Eurasian Plate.
• The Eurasian Plate was compressed and the
sedimentary layer was uplifted to form the Himalayas
• The Himalayas are considered young mountains as they
began to form about 50 million years ago, which is
relatively recent on a geological time scale
Chapter 9: Folding and Faulting

6. Chapter 9: Folding and Faulting
Indo-Australian Plate and
Eurasian Plate moving
towards each other
The sea disappears, the
Himalayas emerge from
the sea, convergence
continues
The sea bed is bent into a
series of folds

7. Types of folds
• Different types of folds are formed depending on the
strength of the compression
Chapter 9: Folding and Faulting
Symmetrical fold
Asymmetrical fold

8. Chapter 9: Folding and Faulting
Overthrust fold Nappe
Overfold Recumbent fold

9. Case Study: Blue Mountains of Jamaica
• The Blue Mountains of Jamaica are evidence of past folding
with much subsequent erosion of the rock strata
Chapter 9: Folding and Faulting

10. Faulting
• Process in which rock masses move along fractures in
the Earth’s crust
• These fractures are called faults
• Three types of faults
– Normal fault (vertical movement)
– Reverse fault (vertical movement)
– Transform fault (horizontal movement)
Block mountains and Rift Valleys
• A complex system of block mountains and rift valleys
may form as a result of varying vertical displacement of
different blocks of rocks
Chapter 9: Folding and Faulting

11. Chapter 9: Folding and Faulting
Normal fault
Reverse fault
Transform fault

12. Block mountains
• Uplifted blocks with steep slopes
• Formed by vertical displacement of rocks at normal faults
(tensional forces) and reverse faults (compressional forces)
Chapter 9: Folding and Faulting

13. Rift valleys
• Elongated areas that
have subsided between
two block mountains
• Deep, with steep walls
• Formed at normal faults
(by tension) and reverse
faults (by compression)
Chapter 9: Folding and Faulting
Formation of rift valley by tension

14. Chapter 9: Folding and Faulting
Formation of rift valley by compression
s

15. Case study: Great Rift
Valley
• Extends 4,800km from
Syria to Mozambique
• Consists of several well-
developed rift valleys,
some of which contain
lakes
• The valleys have
precipitous sides which are
fault scarps
• Formed by violent tectonic
forces that tore apart the
Earth’s crust
Chapter 9: Folding and Faulting

16. • During the tectonic movements, large parts of the crust sank
between parallel fault lines and molten rock was forced up in
volcanic eruptions
• Rifting continues today, with many active and semi-active
volcanoes and hot springs along the Rift
Chapter 9: Folding and Faulting