EES-1000 Lecture 18: Lecture Notes 4
7 Oct 2016
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Deformation: all changes in the original form and/or size of a rock body, most crustal deformation occurs along plate margins! Causes of deformation: stress is the force applied per unit area across an area. A large force per area results in much deformation. A small force per area results in little deformation. There are different types of stress that can be applied when we talk about platectonics we will speci cally talk about horizontal stress: deformation is generated by horizontally directed pressure on a large scale. Shear- blocks of rock sliding past one another! There are two main ways rocks get deformed with compression, extension, and shear. Ductile deformation- rocks deform by ow and folding. A transition between the two occurs at 10 to 15 km depth! Mapping geologic structures: strike- the compass direction of a rock layer as it intersects a horizontal surface, dip- the amount of tilting of the layer and is measured at right angles to strike!
