NATS 1750 Chapter 4: chapter4, portrait of a planet
22 Dec 2017
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Document Summary
Plates: the lithosphere and the outer layer of the earth consists of separate pieces that with respect to one another. The lithosphere lies over a relatively soft layer called asthenosphere. Asthenosphere: composed of mantle that can ow when acted on by a force. The lithosphere is rigid whereas the asthenosphere is like plastic. Lithosphere mantle consists of mantle rock is cooler than 12800 c. Di erence between: continental lithosphere: 25 km to 70 km. Intermediate rock oceanic lithosphere: less than beneath mid oceanic ridges. Lithosphere: discontinuous broken to about 20 pieces, active margins- plate boundaries, passive margins- not plate boundaries, continental crust sediment: 10 - 15 km thick, continental shelf: 500 m thick. Convergent: plates move together, and one subducts the other. 2 to 7 km thick: contains mush of solid mineral crystals and liquid melt which solidi es to become a ma c igneous rock called gabbro. Pillow basalt: consists of piles of meter wide basalt blobs.
