01:460:120 Lecture Notes - Lecture 4: Continental Crust, Heavy Metals, Extrusive Rock
15 Feb 2017
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Document Summary
Some seismic waves - energy associated with earthquakes - can pass through earth. Analysis of these waves reveals much about conditions inside earth. Earth is composed of concentric spherical layers, differing in density. He lithosphere, the outer most solid shell that includes the crust, floats on the hot, deformable asthenosphere. The mantle is the largest of the layers. The core consists of an outer liquid core and a solid inner core the continents are held above sea level by isostatic equilibrium, a process analogous to a ship floating in water. The rigid lithosphere is under strain and when it fractures the result is earthquakes and volcanic eruptions. Early earth was molten and began to differentiate, that is, to stratify based on density of different materials. High density = heavy for its size. Early earth experiences gravitational separation: high density materials (iron and nickel) concentrated in a central "core, less dense material formed concentris spheres around the core.
