OCNG 251 Lecture Notes - Lecture 3: Continental Crust, Oceanic Crust, Asthenosphere
25 Jan 2017
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Document Summary
Crust: thin: 4-60 km, low density minerals. Mantle: 2800 km, higher density minerals (7 times denser) Core: 3500 km from surface to center, highest density. Includes crust and upper most mantle: floating on the asthenosphere. Without, things would just sit still or crack. Asthenosphere: warm, plastic (will flow, upper mantle, capable of changing shape without breaking. Mesosphere: brittle, rigid, lower part of mantle, borders earth"s (cid:272)ore- temperature is significantly higher than layers above, high pressure from weight of earth. Outer core: liquid iron and nickel, causes magnetism and polarity of the earth. Reason for the north and south poles. Inner core: solid iron, extreme pressure and high temperatures preventing liquidity. Continental crust made up of mainly granite: thicker than oceanic, less dense. Oceanic crust made up mostly of basalt: more dense, thinner. Lithosphere includes both types of crust and upper part of mantle. Lithosphere floats on mantle: why plate tectonics occurs, oceanic crust forms and goes under continental.
