GEOL 1250 Lecture Notes - Lecture 2: Plate Tectonics, Mantle Convection, Lithosphere
25 May 2016
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Document Summary
The theory of the earth and how it works. Lithosphere law moves up and down and sideways. If an object is being eroded, part of it is replaced via object below the line (isostatic rebound) Bimodal: surface of the earth is bimodal, 30% is at one elevation, other 70% is at another. Why bimodal? lithosphere = lower density = float higher. Difference in chemical and physical composition - continental. Ocean: high density, thin layer of rock. Continent: low density, thick layer of rock. Multiple plates/ fragments on surface of the earth. Transfer of heat and motion of material. As long as there is a difference in temperature on top and bottom, mantle convection is moving. The mantle moves in a circular motions (opposite directions on one side, same direction on the other) causing horizontal movement (mantle upwelling) < divergent plate margin. 2 plates move away, causes seafloor spreading. Mantle cools down and gets dense, tends to sing (downwelling or subduction)
