Earth Sciences 1022A/B Lecture Notes - Lecture 1: Convergent Boundary, Geosphere, Hydrosphere
9 Jan 2017
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Geology is important for energy and natural resources solving environmental problems, building cities and highways, predicting and protecting against natural disasters like earthquakes, volcanic eruptions, landslides and floods. Uniformitarianism the fundamental principle the present is the key to the past . The processes we see going on the surface of our planet have always gone on. Geologic time is measured in billions of years. After the big bang (14 billion years ago), earth may have formed by the nebular theory. Nebular theory 5 billion years ago. Nebula (cloud) of hydrogen and helium contracted under gravity into the flat disc of our solar system. Within the disc, earth evolved through many collisions of rocky and metallic fragments into a rocky sphere divided into a dense core, larger mantle, and lighter crust. The nebula spins and pulls heavy particles in and light out. Definition curst and uppermost mantle formed rigid plates of lithosphere and asthenosphere.
