GEOS 170A1 Lecture Notes - Lecture 6: Silly Putty, Plate Tectonics, Asthenosphere
6 Aug 2018
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Recap: the lithosphere and crust are related: the lithosphere contains the crust (and uppermost mantle, lithosphere/asthenosphere is layering based on strength behavior. Strength layering: plate tectonics: lithosphere (strong!, crust plus the uppermost mantle, lithosphere = plate, 100 - 200 km thick. Lithosphere overlies asthenosphere (weak!: asthenosphere is solid (not molten) but can flow like silly putty, asthenosphere is 100 - 300 km thick. The layered earth: summary: strong lithosphere (brittle) over weak (not molten) asthenosphere (plastic, chemical layering: crust + mantle + core. History: matching fossils, matching rocks (types & ages, no mechanism, world war ii. Plate tectonics: earth = broken egg shell, plate = piece of lithosphere that moves, asthenosphere is solid that can flow. Earth is cooling: cooling creates density differences - sinking & rising, mantle is a solid that can flow, center is hot, the heat mostly comes from transition from liquid to solid in core.
