Plate Tectonics: Part II Folding and Faulting. CGC 1D1. Horizontal movements of the Earth’s Crust. Takes place from compression and tensional forces Tension – stress tending to pull rock masses apart Compression – Stress tending to squeeze rock masses together
The Valley of Ten Peaks, Banff National Park
Normal faults occur when tensional forces act in opposite directions and cause one slab of the rock to be displaced up and the other slab down
Reverse faults develop when compressional forces exist
Compression causes one block to be pushed up and over the other block.
A graben faultis produced when tensional stresses result in the subsidence of a block of rock. On a large scale these features are known as Rift Valleys
A Rift Valley may be formed in two ways :
Barron Canyon in Algonquin Park is along a fault associated with the Ottawa Bonnecheregraben.
A horst fault is the development of two reverse faults causing a block of rock to be pushed up
- In German Horst = 'heap'