7: Geologic Structures
- Page ID
- 36909
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Crustal deformation occurs when applied forces exceed the internal strength of rocks, physically changing their shapes. These forces are called stress, and the physical changes they create are called strain. Forces involved in tectonic processes as well as gravity and igneous pluton emplacement produce strains in rocks that include folds, fractures, and faults. When rock experiences large amounts of stress and breaks, energy is released in the form of seismic waves, commonly known as an earthquake. Whether a rock respond by folding or faulting (breaking) tells geologists a lot about the conditions it was under at the time stress was applied and helps them construct the geologic history of an area.
Thumbnail: Folds of alternate layers of limestone and chert. By Dieter Mueller (dino1948), shared under CC BY-SA 4.0.