Bedrock

In addition to the occasional mineral crystal or fossil that attracts rockhounds, all outcrops contain through-going fractures called joints. These form during the application of stresses to bedrock on a regional scale, for example during mountain-building. Even greater stresses may cause faulting movement of the rock on the sides of a fracture. An example is the large-scale bedrock movement that occurs along the San Andreas Fault in California. When stresses cause plastic rather than brittle deformation of bedrock, it folds rather than faulting.