1. Deforming the Earth’s Crust

2. Stress
The amount of force per unit of area on a given material.

3. Deformation
The process by which the shape of a rock changes because of the stress on it.

4. Compression
The type of stress that occurs when an object is squeezed, such as when two plates collide.

5. Tension
The type of stress that occurs when forces act to stretch an object such as at a divergent boundary.

6. Folding
The bending of rock layers because of stress in the Earth’s crust.

7. Anticlines and Synclines
Anticlines – Upward arching folds in rock
layers
Synclines – Downward, trough-like folds in
rock layers

8. Fault The surface along which rocks break and slide past each other
The blocks of crust on each side are called fault blocks.
Fault

10. Hanging Wall and Foot Wall

11. Normal Fault The hanging wall moves down relative to the footwall.
Usually occur under tension (divergent boundary)

12. Reverse Faults The hanging wall moves up relative to the footwall.
Usually occur under compression (convergent boundary)

13. Strike –Slip Fault
When opposing forces cause rock to break and move horizontally.
The San Andreas fault in California is an example.

14. Folded Mountains
The tallest mountains in the world are made of folded mountains.
Form at convergent boundaries
Examples:
Appalachian Mountains (North America)
Alps (Europe)
Ural Mountains (Russia)
Himalayas (Asia)

15. Fault-Block Mountains
When tension causes large blocks of the Earth’s crust to drop down relative to other blocks.
Example: Tetons in western Wyoming

16. Volcanic Mountains

17. Volcanic Mountains Continued…
Most are located at convergent boundaries where oceanic crust sinks into the asthenosphere at subduction zones.
The rock is melted, forms magma, then rises to the surface and erupts to form volcanic mountains.

18. Ring of Fire
The majority of tectonically active volcanic mountains on the Earth have formed around tectonically active rim of the Pacific Ocean.
This has been known as the “Ring of Fire”.

19. Uplift and Subsidence Uplift - The rising of regions of Earth’s crust
to higher elevations.
Subsidence – The sinking of Earth’s crust
to lower elevations.