chapter_17_le modified

chapter_17_le modified - Earths Interior and Geophysical...

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Steve Kadel, Glendale Community College Earth’s Interior and Geophysical Properties Physical Geology 11/e, Chapter 17
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Introduction Deep interior of the Earth must be studied indirectly Direct access only to crustal rocks and small upper mantle fragments brought up by volcanic eruptions or slapped onto continents by subducting oceanic plates Deepest drillhole reached about 12 km, but did not reach the mantle Geophysics is the branch of geology that studies the interior of the Earth
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Evidence from Seismic Waves Seismic waves or vibrations from a large earthquake (or underground nuclear test) will pass through the entire Earth Seismic reflection - the return of some waves to the surface after bouncing off a rock layer boundary Sharp boundary between two materials of different densities will reflect seismic waves Seismic refraction - bending of seismic waves as they pass from one material to another having different seismic wave velocities
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Earth’s Internal Structure Seismic waves have been used to determine the three main zones within the Earth: the crust , mantle and core The crust is the outer layer of rock that forms a thin skin on Earth’s surface The mantle is a thick shell of dense rock that separates the crust above from the core below The core is the metallic central zone of the Earth
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The Crust Seismic wave studies indicate crust is thinner and denser beneath the oceans than on the continents Different seismic wave velocities in oceanic (7 km/sec) vs. continental (~6 km/
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This note was uploaded on 06/13/2011 for the course GEOL 1403 taught by Professor Mulcahey during the Spring '11 term at Lone Star College System.

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chapter_17_le modified - Earths Interior and Geophysical...

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