ERTH 2415 Lecture Notes - Lecture 5: North American Plate, Supercontinent, Outer Core
26 Sep 2015
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Document Summary
Thin, less dense crust rich in silicon and oxygen. Very dense iron-rich metallic core: earth can be described as a series of layers where less dense material floats on top of denser material. Continental crust has lower density than oceanic crust. Low-density crust floats on top of the denser mantle. Mantle is supported by the very dense core: strength layers: Rigid lithosphere (solid, could break with hammer) Plastic mesosphere: more viscous than asthenosphere. Solid inner core: low-density and rigid lithosphere floats on top of denser and plastic asthenosphere, lithosphere-asthenosphere boundary at a depth of 100 km, convection - heat transfer by fluid circulation. Internal geomagnetic field due to movement of liquid iron in outer core: earth"s rotation, heat transfer by convection at the outer-inner core boundary. Age of ocean basins: no oceanic crust older than 200 ma, oceanic crust constantly being recycled. Hypocenter - point of origin of an earthquake in the subsurface.
