Earth Sciences 1022A/B Lecture Notes - Lecture 1: Plate Tectonics, Cottage Country, Canadian Shield
24 Mar 2015
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Uniformitarianism the present is the key to the past . So what we see in geology today, likely occurred in the past. We think the earth has been around for billions of years. Scientific viewpoint is about 4. 5 billion years (religious viewpoints will differ from this number) If we look at the canadian shield (muskoka, cottage country) that area, billion of years ago was mountainous with mountains as high as the rockies, but over the years it has become flat. Nebula (cloud) of hydrogen and helium contracted under gravity into the flat disc of our solar system (gradually flattened disc eventually formed our solar system); we think the earth was formed by rocky and metallic collisions rrt. Crust and uppermost mantle formed rigid plates of . Asthenosphere which moves by convention (the asthenosphere is lighter and under higher pressure, hot*) Crust + the uppermost mantle = lithosphere (see diagram) Came up with the idea of continental drift .
