Test 1 Notes

Test 1 Notes - Chapter 3 Mantle- layer beneath the crust...

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Chapter 3 Mantle- layer beneath the crust composes 68% of earth’s mass and 83% of earth’s volume. - Mantle materials contain silicon, oxygen with iron and magnesium - Average density is 4.5 g/cm3 - Mantle is about 1800 miles thick Core- consists mainly of iron - 90% iron and nickel, along with silicon, sulfur, and heavy elements. - Average density is 13g/cm3 - Radius is 2160 miles - Accounts 31.5% of earth’s mass and about 16% of its volume Different conditions of temp and pressure prevail at different depths and these conditions influence the physical properties of the materials subjected to them. Lithosphere- is earth’s cool, rigid outer layer (60-125 miles) thick. - Comprises the continental and oceanic crusts and the uppermost cool and rigid portion of the mantle. Asthenosphere- is the hot partially melted slowly flowing layer of the upper mantle below the lithosphere. (220-400miles) Lower Mantle- extends to the core. The asthenosphere and the mantle below the asthenosphere have a similar chemical composition. Although, it is hotter because of rapidly increasing pressure the mantle below the asthenosphere does not melt. As a result, it is denser and flows more slowly. Core- outer core is a dense, vicious liquid. The inner core is a solid with a maximum density about 16g/cm3. - The solid inner core also rotates eastward at a slightly faster rate than the mantle. Buoyancy- ability of an object to float in a fluid by displacing a volume of that fluid equal in weight to the floating object’s own weight. - Buoyancy of an object depends on its density and it’s mass.
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The continents mountains float high above sea level because the lithosphere gradually snicks into the deformable asthenosphere until it has displaced a volume of asthenosphere equal in mass to the mountain’s mass. Radioactive decay- most atoms are stable and do not change, some forms of elements are unstable and give off heat when their nuclei break apart (decay). Radioactive particles are ejected in the process. - Radioactive decay within the newly formed earth released heat that contributed to the melting of the originals mass. Most of the melted iron sank toward the core, releasing huge amounts of energy. This residual heat combines with the much greater heat given off by the continuous decay of radioactive elements within the crust and upper mantle. Conduction- earths internal heat journeys toward the surface by conduction. Convection- some heat rises in asthenosphere and mantle. - Occurs when fluid or semisolid is heated and expands and becomes less dense and rises. Uniformitarianism- suggest that all earth’s geological features and history could be explained by processes identical to ones acting today and that these processes must have been at work for a long time Catastrophism- Pangaea- Wegener suggested that all earth’s land had once been joined into a single supercontinent surrounded by an ocean. ( Panthalassa- surrounding ocean) ---scientists found that the ocean bottom nearly always sloped gradually out to sea for some
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This note was uploaded on 03/22/2011 for the course OCS 1005 taught by Professor Condrey during the Spring '08 term at LSU.

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Test 1 Notes - Chapter 3 Mantle- layer beneath the crust...

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