208_Lect05b_color - 1 1. Seafloor Spreading Evidence &...

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Unformatted text preview: 1 1. Seafloor Spreading Evidence & Theory 2. Subduction - evidence 3. Theory of Plate Tectonics Median ridge Median ridge Bathymetry of seafloor Bathymetry of seafloor Evidence for Seafloor Spreading. Wegener did not know these things… H. Hess proposes Theory of Seafloor Spreading in 1962 Hess’s main line of evidence: submerged flat-topped seamounts become deeper away from the ride axis 2 Example: Louisville, Austral-Cooks, Tahiti seamount chains Easter Is. Juan Fernendez The Theory of Seafloor Spreading: • Lithosphere ‘ripped’ apart at Mid-Ocean Ridge – Mechanism? - hold your horses • Asthenosphere rises beneath the thinned Lith. – expands thermally and lifts (forms) ridge – Melts to produce volcanoes underlying ridge • Volcanic system on the MOR creates new crust • New crust rafted away as spreading continues This is not how Hess understood it, rather this is the current theory Draw: Draw: Sediment Sediment Fossil age Fossil age Heat flow Heat flow 3 1....
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This note was uploaded on 05/26/2011 for the course GEOL 208 taught by Professor Michaelstuart during the Spring '11 term at Moraine Valley Community College.

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208_Lect05b_color - 1 1. Seafloor Spreading Evidence &...

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