Deformation. - the process by which the shape of a rock changes because of stress is called deformation. Deforming the Earth’s Crust. compression : stress that occurs when forces act to squeeze an object at a convergent boundary. 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)
- when rocks are moved horizontally by opposing forces, strike-slip faults often form. (San Andreas Fault)
- 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.
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
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
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.
- rocks that subside do not
undergo much deformation
- subsidence can also
occur when the
stretched in rift zones.
- rift zones are sets of
deep cracks that form
between two tectonic
plates that are pulling
away from each other