HW3 - GLG244.A HW#3 DUE: Tuesday, October 4th Name:...

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GLG244.A HW#3 Fall 2011 DUE: Tuesday, October 4 th Name: ___Lindsey Duff__ Score: /75 What role does plate tectonics play in shaping our oceans and coastlines? Article to read (posted in Niihka): Nance, R.D., Worsley, T.R., and Moody, J.B. 1988. The Supercontinent Cycle in Shaping the Earth Tectonics of Continents and Oceans , p. 177-187. Questions to be answered. All responses are to be typed. 1. According to this article, what is the theory of plate tectonics? o The Earth’s rigid outer layer (lithosphere) is a mosaic of slab-like plates that move with respect to one another at speeds averaging a few centimeters per year. o The plates float on a hot, plastic layer of the earth’s mantle (asthenosphere) 2. According to this article, what are the driving forces of plate motion? o Heat is the dominant force The convective motions in the underlying mantle that are powered by heat from the decay of radioactive elements drive plate tectonics o Supercontinent cycle o Sea-floor spreading: molten material from the asthenosphere rises though the lithosphere at high ridges on the ocean floor, where it cools to become new crust If the sea floor and the adjacent continent are on the same plate, the continent is carried along the conveyor belt of oceanic crust Subduction can occur also: oceanic crust can sink under the continent to rejoin the mantle 3. What is a “supercontinent”? o
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HW3 - GLG244.A HW#3 DUE: Tuesday, October 4th Name:...

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