deformationI - Physical Geology 101 19. Crustal Deformation...

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Physical Geology 101 1 19. Crustal Deformation I (p. 274-278; 288-292) Introduction Although the Earth is 4.6 billion years old, most of the oldest rocks on Earth have long since vanished, so we see more younger rocks than older rocks. So the older rocks must have been removed by processes like weathering, erosion, and the effects of plate tectonics. Some rocks were deeply buried and turned into metamorphic rocks. Where do we see deeply formed metamorphic rocks that now form mountain ranges? ___________________ All over the world, rocks that were once perfectly flat lying are often inclined at a range of angles or are warped. They are also often intensely fractured and may contain abrupt breaks called ______________ across which one block of rock slides past another block. These different types of features are called deformation features . We need to know how to describe them, how they formed, and what they can tell us about the geologic history of a region. The field of geology that considers deformation of rocks is called __________________. It is vital for understanding what happens to rocks in response to the huge forces that occur inside the Earth's crust as a result of plate tectonics. Rock Deformation When we looked at metamorphic rocks, we learned why a foliation develops in a rock. Foliation is produced by forces pushing against rocks, but the force cannot be the same from all directions. To produce a foliation, we need to have forces being different from different directions- this is called a ______________________. This gets produced by the interactions and motions of the tectonic plates. These motions produce stresses that we call tectonic stresses , which are different from different directions, resulting in differential stress. As a result, rocks get deformed. Rock deformation refers to all the different ways that rocks respond to squeezing, stretching, or any other kind of tectonic force. This deformation may involve:
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This note was uploaded on 01/13/2012 for the course GEOL 101 taught by Professor Williams,t during the Fall '08 term at Idaho.

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deformationI - Physical Geology 101 19. Crustal Deformation...

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