ESC 1000 Lecture Notes - Lecture 2: Igneous Rock, Seafloor Spreading, Supercontinent
19 Apr 2016
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Document Summary
2b - chapter 8: mountains, basins, and continental margins. Regional elevations are controlled primarily by the thickness of the crust, but they can also be influenced by the temperature and density of materials in the crust and upper mantle. Differences in crustal thickness between regions reflect differences in their geologic histories. Such differences include whether the crust is continental or oceanic, and whether it has been deformed, eroded, or buried. Continents have thick crest (30-50 km) and are higher than ocean basins, which are underlain by oceanic crust which is thinner (7 m) Decreasing elevation: normal faulting can thin the crust by displacing higher rocks off lower ones. This decreases crustal thickness and causes a region to subside. Increasing elevation: crust that is compressed and shortened by thrust faults also thickens. This thickening causes the region to be uplifted. The thrust can also uplift rocks, forming a mountain.
