450 likes | 2.73k Views
Diastrophism. Results of plate tectonics: 1.volcanism 2.diastrophism 3.earthquakes. diastrophism:. Deformation of crust due to tectonic stress: Folding (bending) Faulting (breaking and displacement). Types of Stress and Strain.
E N D
Diastrophism Results of plate tectonics: 1.volcanism 2.diastrophism 3.earthquakes
diastrophism: • Deformation of crust due to tectonic stress: • Folding (bending) • Faulting (breaking and displacement)
Types of Stress and Strain (Stress is force acting on rock; strain is rock’s response to stress) • Compression (shortening) • Extension (stretching)
EXTENSION COMPRESSION
Folding • Compressional stress causes rocks to buckle and fold • Anticline: arch-shaped fold • Syncline: sink-shaped fold
Differential erosion leads to: • Anticlinal ridges and valleys • Synclinal ridges and valleys • Differential erosion: less-resistant types of rock strata will weather and erode more rapidly than more-resistant rock strata
Anticlinal mountain/ridge Synclinal valley
What’s this? Synclinal mountain/ridge
Faulting • Rock is strained beyond ability to remain intact; rock fractures; one side is displaced with respect to the other . • Fault plane: surface along which 2 sides move • Fault scarp: cliff formed along fault face
Fault from Hebgen Lake, Montana earthquake, 1959 What’s this? Fault scarp
Types of Faults 1. Normal Fault: from extensional stress Vertical movement along an inclined fault plane
Horst and Graben(result of normal faulting) Horst : up-faulted block Graben: down-faulted block
2. Reverse Fault from compressional stress Vertical movement along inclined fault plane such that one side rides up over the other. often creates landslides
3. Overthrust fault • Reverse fault with very low angle • More horizontal than vertical movement
3. Transcurrent (Strike-slip) Fault horizontal movement no fault scarp
Transcurrent HEY! Who moved my wood pile?!@*