3-OcFA11-TectonicsWEB

3-OcFA11-TectonicsWE - Plate Tectonics Unifying theory of geology Affects almost every aspect of the science Evolved since the 1960s(young Combines

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Plate Tectonics Unifying theory of geology Affects almost every aspect of the science Evolved since the 1960’s (young!) Combines 2 pre-existing theories: Continental drift Seafloor spreading The outer shell of the earth, the lithosphere, is made up of a few of internally rigid plates (~12) Plates in constant motion relative to each other. Plates float on the fluid mantle Geological features formed by the movement of plates and their interactions along their edges (plate boundaries). Continental Drift Theory developed by Wegner (1912) that the continents were once part of a supercontinent (Pangaea) and have moved to their present positions Evidence Puzzle-piece Fit Occurrences of fossils, climate indicators on matching coastlines Occurrences of mountain ranges, rock types, on matching coastlines Glacier movement Problem: how do they move? Wegner: Continents “Plowed” through the ocean floor improbable, what forces?
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Seafloor Spreading New tools and new evidence Harry Hess, 1960 proposes that new seafloor forms at ocean ridges Continents moved (pushed) as the new seafloor is added Source of energy = convection in the mantle Evidence Seafloor Features Shape, Location of Mid-Ocean ridges (mid-ocean ridge shape matches continental margin shape) Paleomagnetic Pattern Seafloor Striping Radiochronometry Seafloor Age distribution (seafloor rock age increases away
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This note was uploaded on 12/04/2011 for the course OCE 1001 taught by Professor Smith during the Fall '08 term at University of Florida.

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3-OcFA11-TectonicsWE - Plate Tectonics Unifying theory of geology Affects almost every aspect of the science Evolved since the 1960s(young Combines

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