1. Ch.4, Sec.4 - 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. Ch.4, Sec.4 - Deforming the Earth’s Crust
tension: stress that occurs when forces act to stretch an object at a divergent & transform boundary.

3. Ch.4, Sec.4 - 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

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2. syncline – downward channel-like folds
3. monocline – both ends of the folds are horizontal in pattern

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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.

7. Ch.4, Sec.4 - 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)

8. Ch.4, Sec.4 - Deforming the Earth’s Crust
What kind of fault is this, normal or reverse?
Answer: Reverse Fault (hint: the hanging wall is above the footwall)
What kind of plate boundary is causing this fault?
Answer: Convergent
What kind of force is causing this fault?
Answer: compression

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- when rocks are moved horizontally by shearing forces, strike-slip faults often form. (San Andreas Fault)
Plate

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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

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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

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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

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Honolulu, Oahu
Mauna Kea is the tallest
mountain in the world at
over 36,000 feet!
The Hawaiian Islands are some of the youngest volcanic mountains forming right now.

17. Ch.4, Sec.4 - 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

18. Ch.4, Sec.4 - 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