Folding and Faulting
Diastrophic processes - folding and faulting occur when pressure deep within the lithosphere cause the earth=s surface to buckle, bend and even split apart.
Folding - when the earth=s crust is pushed up from its sides
- occurs at a very slow rate
- Fold mountains occur where the crust is pushed up as plates collide which causes the crust to rise up in folds.
Examples: Andes, Himalayas, Juras in Switzerland, Appalachians
Types of Folds 1. Anticline- the peak or hill of folded rock layers
2. Syncline - the trough or valley of folded rock layers
3. Tight fold - a sharp-peaked anticline fold
4. Overfold - bending or warping of folding rock layers
5. Recumbent fold - a fold that is bent so much that it is no longer vertical.
6. Nappe - a fold that has overturned so much the rock layers have fractured.
Faulting - when tension and compression associated with plate movement is so great that blocks of rock fracture or break apart.
- process can occur very rapidly
- this rapid movement causes the ground to shake and vibrate, resulting in earthquakes.
Types of Faults 1. Normal - rocks move away from each other due to land moving apart.
2. Rift valley/graben -two normal faults occur parallel to each other and the land sinks between the two faults
3. Reverse Fault - opposite of normal; rocks are compressed such that one plate moves up while the other decends below it
4. Horst - land rises between parallel faults.
5. Tear fault/strike-slip - two plates slide laterally past each other.