Monday, November 9, 2009

Earth's Structure

Earth's Structure-Unit Review
From inside (the center) to out (the surface)...
Core-
-spherical mass composed of metallic iron and nickel
-15% of Earth
-DENSEST layer
Contains:
-Outer Core: rotating molten iron; generates magnetic field
-Inner core: solid iron (due to high pressure) and partly nickel
Mantle-
-surrounds the core
-84% of Earth
-mainly igneous rock/-->soft: not liquid but not solid
Contains:
-Lithosphere: includes crust and upper mantle; cool, solid, and rigid; contains plates
-Asthenosphere: includes upper/middle mantle; under lithosphere; rocks are like 
plastic-->soft due to pressure and heat-->do not melt!
-Mesosphere: lower mantle; varies in composition.
Crust-
-thin and rigid
-1% of Earth
-layers of light rock that surrounds mantle-->igneous, sedimentary, and metamorphic rocks
Contains:
-Oceanic: Basalt (extrusive); young rock, sits below and is denser than continental crust
-Continental: Granite (intrusive); older rocks, less dense than oceanic crust.

Evidence as to what the layers of Earth are made out of come from...
-Seismic Wave Data
-Lava that has extruded onto the surface
-Iron meteorites

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