Exam 2 Study Guide

Exam 2 Study Guide - Taylor Chestnut GOL 105 3/4/08 Earth...

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Taylor Chestnut GOL 105 3/4/08 Earth Science - Exam 2 EARTHS COMPOSITION Earth is made up of the crust, mantle, inner core, and outer core. The radius is 6400 km. Oceanic Crust – Basalt, dense, thin o Basalt is a fine grained, dark, igneous rock Continental Crust – Granite, lighter, thick Everything underneath the crust is called the mantle, the layer separating the two is the Moho (Mohorovic Discontinuity – increase in density) Isotasy – less dense materials float on higher density o Oceanic and Continental crust float on the mantle because they are less dense. o Iceberg Effect Icebergs less dense then water so they float Larger blocks sit higher but float lower too. (Mountain belts sit lower in the mantle) Lithosphere – Crust + top of mantle, rigid. Possible because mantle and crust have similar properties. Asthenosphere – Upper mantle, flows o Lithosphere cracks under pressure, asthenosphere does not Core – Made from Iron and Nickel, inner is solid/outer is liquid. VERY DENSE o The circulation of Iron in outer core is how earth’s magnetic field is generated. Polarity flips back and forth (recorded in rocks) PLATE TECTONICS The continents are not fixed in place! Alfred Wegner – puzzle pieces, similar rocks, proposed idea of continental drift. o Mesosaurus is a reptile fossil found on S.A. and Africa but nowhere else. o Many fossils make more sense if the countries were pushed together. o There is evidence on glaciers on southern parts of most continents but some are now tropical. o Pangaea = Super Continent Evidence for continental drift o Similar outlines of continents o Rocks correlate o Same fossils o Glacial deposits match up Didn’t know what the mechanism was until found out about the ocean floor and mid-ocean ridges. Mid-Ocean Ridges:
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o Long linear mountain chains running down middle of oceans. There are stripes of magnetic polarity on either side that are the same age. o Stripes get older as you move away from spreading center, further you are from the ridge the older the rocks are, youngest rocks are on top of ridge. o The mid-Atlantic ridge comes to the surface in Iceland!! Sea Floor Spreading:
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Exam 2 Study Guide - Taylor Chestnut GOL 105 3/4/08 Earth...

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