EARTHSC 1G03 Lecture Notes - Lecture 2: Plate Tectonics, Continental Crust, Oceanic Crust
5 Apr 2017
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Document Summary
Modern continents move slowly over the glove and have formed from the break up of pangea over 200 million years. There was no known mechanism for the continents to plow through the rigid oceanic crust. Former glaciers appear to have moved out from the middle of the ocean. But glacial ice doesn"t form in the ocean. If the continents fit together into pangea, the glacier moved out from the south pole. Magnetic minerals in lava rotate with the earth"s magnetic field. As laca cools, small magnetite minerals freeze in place. At equator magnet is pulled equally, in opposite directions. From rocks, we can reconstruct how far away the poles were and in which direction. Water escaping underneath the upper continental plate from the ocean rock, releases hot water that melts the rock underneath the continental plate creating magma (stuff underneath, lava is when it comes out) Continental convergence leads to extremely high topography at early stages.
