1. Deforming the Earth’s Crust
Deformation
- the process by which the shape of a rock changes because of stress is called deformation.
compression: stress that occurs when forces act to squeeze an object at a convergent boundary.

2. Deforming the Earth’s Crust
tension: stress that occurs when forces act to stretch an object at a divergent boundary.

3. Deforming the Earth’s Crust
Folding
folding: the bending of rock layers due to stress.
- the three most common types of folds (pg.113) are:
1. anticline – upward arching folds

4. Deforming the Earth’s Crust
2. syncline – downward channel-like folds
3. monocline – both ends of the folds are horizontal in pattern

5. Deforming the Earth’s Crust
Faulting
fault: a break in a body of rock along which one block slides relative to another.
- fault blocks can be either hanging walls or footwalls.

6. Deforming the Earth’s Crust
- when normal rocks are pulled apart because of tension, normal faults often form. (African Rift)
- when rocks are pushed together by compression, reverse faults often form. (Himalayas & Alps)

7. Deforming the Earth’s Crust
- when rocks are moved horizontally by opposing forces, strike-slip faults often form. (San Andreas Fault)
Plate

8. Deforming the Earth’s Crust
Plate Tectonics & Mountain Building
- mountains exist because tectonic plates are continually moving & colliding with each other.
- three most common types of mountains are:
1. folded mountains (pg.116) – these form when rock layers are squeezed together & pushed upward.
Ushuaia, Argentina
Matterhorn, Switzerland

9. Deforming the Earth’s Crust
2. fault-block mountains (pg.117) – these form when tension causes large blocks of the Earth’s crust to drop down relative to other blocks.
Grand Tetons, Wyoming

10. Deforming the Earth’s Crust
3. volcanic mountains (pg.117) – these form when rock that is melted in subduction zones forms magma, which rises to the Earth’s surface through eruptions.
Mount Fuji, Japan
Mount St. Helens, Washington

11. Deforming the Earth’s Crust
Honolulu, Oahu
Mauna Kea is the tallest
mountain in the world at
over 33,000 feet!
The Hawaiian Islands are some of the youngest volcanic mountains forming right now.

12. Deforming the Earth’s Crust
Uplift and Subsidence
uplift: the rising of regions of the Earth’s crust to higher elevations.
subsidence: the sinking of regions of the Earth’s crust to lower elevations.
- rocks that subside do not
undergo much deformation

13. Deforming the Earth’s Crust
- subsidence can also
occur when the
lithosphere becomes
stretched in rift zones.
- rift zones are sets of
deep cracks that form
between two tectonic
plates that are pulling
away from each other