Chapter 3

Chapter 3 - Marine Systems Chapter 3 Chapter 3 Earth...

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Marine Systems Chapter 3 Chapter 3 Earth Structure and Plate Tectonics I. Earthquakes and Earthquakes Waves -Low- frequency pulses of energy generated by the forces that cause earthquakes- seismic waves - can spread rapidly into Earth in all directions and then return to the surface. - Seismographs - instruments that sense and record earthquakes Some seismic waves—energy associated with earthquakes—can pass through earth. Analysis of how these waves changed, and the time required for their passage, has told researchers much about conditions inside our planet II. A layered Earth - The uppermost layer of the earth is the lightweight, brittle, aptly names crust. - The thin oceanic crust is primarily basalt , a heavy, dark-colored rock composed of mostly oxygen, silicon, magnesium, and iron. - The most common material in the thicker continental crust is granite , a familiar speckled rock composed mainly of oxygen, silicon, and aluminum. - The mantle , the layer beneath the crust, is though to consist mainly of oxygen, iron, magnesium, and silicon. - The behavior of a rock is determined by three factors: temperature, pressure, and the rate at which a deforming force (stress) is applied. - The lithosphere earth’s cool, rigid outer layer – is 100-200 KM in thickness. It comprises the continental and oceanic crusts and the uppermost cool and rigid part of the mantle. - The asthenosphere is the hot, partially melted, slowly flowing layer of upper mantle below the lithosphere extending to a depth of about 150-659 KM - The lower mantle extends to the core. The asthenosphere and the mantle below the asthenosphere have similar chemical composition. Although it is hotter, mantle below the asthenosphere dot not melt because of the rapidly increasing pressure. As a result it is more sense and flows much more slowly. -
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Chapter 3 - Marine Systems Chapter 3 Chapter 3 Earth...

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