GEO-100 (Cain) Plate Tectonics

GEO-100 (Cain) Plate Tectonics - Chapter 3: Plate Tectonics...

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Chapter 3 : Plate Tectonics Asthenosphere and Listhosphere : Lithosphere – The outer solid layer of the earth. (The earth’s crust and uppermost mantle.) - It varies in thickness from place to place on the earth. - It is thinnest underneath the oceans, where it extends to a depth of 50 kilometers (30 miles). - It is thicker underneath the continents is thicker, extending in places over 100 kilometers (60 miles) Asthenosphere – The layer below the lithosphere. (Mantle) - It extends an average depth of 300 kilometers (close to 200 miles) in the mantle. - It lacks strength or rigidity from a combination of high temperatures and moderate confining pressures that allows the rock flow plastically under stress. Below the asthenosphere, as pressures increase faster than temperatures with depth, the mantle again becomes more rigid and elastic. - The asthenosphere was discovered by studying the behavior of seismic waves from earthquakes. Its presence makes the concept of continental drift more plausible. The continents need not drag across solid rock; instead, they can be pictured
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GEO-100 (Cain) Plate Tectonics - Chapter 3: Plate Tectonics...

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