ERTH 20 Lecture Notes - Lecture 23: Oceanic Trench, Plate Tectonics, Divergent Boundary
2 Dec 2020
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Plate tectonic theory lithosphere is broken into plates or pieces. Outermost layer of earth is strong layer called lithosphere. Plates are moving relative to each other. By strength- lithosphere (plate: cold, strong, rigid, brittle. Divergent boundary move away; split apart. Lithoshpere- asthenosphere: we can also regard layering based on rock strength ( rheology , lithosphere- the outermost 100-150km of earth, asthenosphere-upper mantle below the lithosphere. Convection- heated material becomes less dense and rises denser cold material sinks. Conduction- transfers heat along a metal rod. Divergent plate boundaries- two types- one in middle of ocean- other in the middle of a continent. Margins far from plate boundaries are passive . Subduction zone when the plates divide into each other also produce mountains and volcanoies. All trenches in ocean are at subduction zones. Ring of fire- called that because of volcanoes all around that. Contintental lithosphere is very hard to subduct. Transform plate boundaries-plates are moving side by side.
