Earth Crust Deformation

1. Earth Crust Deformation Caused by stresses in the crust

2. Opposing forces • Creates Strike slip faults as one side of the fault slips past the other. (side swipe) • Can occur at transform plate boundaries. • Crust is not created or destroyed and there is no up or down movement. • Ex: San Andreas fault

3. Tension • Can cause stretching of crust until it breaks and creates faults • Causes normal faults where the foot wall moves up in relation to the hanging wall • Creates fault block mountains such as the Canadian rockies and the Grand Teton Mountains in western Wyoming • Can cause volcanoes especially at divergent plate boundaries. Ex: Iceland • Can occur at divergent plate boundaries.

4. Compression • Forces pushing together can cause folding of rock layers • Anticlines are the top of the fold; synclines are the bottom of the fold. • Creates reverse faults where the hanging wall moves up in relation to the foot wall. • Creates folded/ faulted mountains like the Himalayas or the Appalachian Mountains when 2 continents collide • Can create volcanoes near a subduction zone. Ex: Alaskan volcanoes; Japanese and Phillipine volcanoes. • Can occur at convergent plate boundaries.

5. Uplift and Subsidence • Created by vertical forces within Earth’s crust. • Uplift is when a region of Earth’s crust is elevated due to mountain building or due to springing back when a weight is removed from Earth’s crust • Can create monocline folds. • Subsidence, or sinking can occur when rocks cool because cool rocks generally contract. It can also occur at divergent rift zones when blocks of crust slip down on normal faults