GEOS 170A1 Lecture Notes - Lecture 6: Silly Putty, Plate Tectonics, Asthenosphere
31 Jan 2017
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Document Summary
It is solid (not molten) but can flow like silly putty. Strong lithosphere over the weak asthenosphere (plate tectonics) Plate tectonics has the best way of dumping heat into the mantle. Mantle is a solid that can flow (think oreo cookie filling) New plate is created at ridges, old plates are removed at subduction zones. Plate=piece of lithosphere that moves (parts between edges of broken egg shell) Plates are defined by their boundaries (plate edges), not continents or shorelines. Where two boundaries slide past each other. As plates spread, forms a whole and the asthenosphere flows up to fill the gap. Doesn"t harden until it hits the surface. Plates diverge at about 3-10 cm per year. Material from below is less dense so it moves up, melts before it hits surface, then cools and solidifies, thus creating a new plate. ~85% of all volcanic activity occurs at mid-ocean ridges.
