TAMU GEOL 101 - Geology 101 Class Day 3 (5 pages)

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Geology 101 539 Class 3 Test 1 Tuesday September 9 2014 Outline Recap Rates and history of plate movements o Paleo magnetism recorded in rocks o Seafloor as a magnetic tape recorder The grand reconstruction o Seafloor isochrones o Reconstructing the history of plate movements Mechanism of plate tectonics o Mantle convections mantle plumes Plate Tectonics Involves the outer portion of earth crust and topmost part of the mantle down to the asthenosphere o About 20 distinct plates o Tens of km in thickness o In relative motion with respect to each other Plate motion causes earthquakes builds mountain ranges and volcanic activity 3 Type of Plate Boundaries Divergent Boundaries o Oceanic spreading center Rifting and spreading along a mid ocean ridge create new oceanic lithosphere Mid Atlantic ridge o Continental rift zone Rifting and spreading zones on continents are characterized by parallel rift valleys volcanism and earthquakes Great Rift Valley Convergent o Ocean Ocean Convergence Where oceanic lithosphere meets oceanic lithosphere one plate is sub ducted under the other and a deep sea trench and volcano is formed o Ocean Continent convergence Peru Chile trench When oceanic lithosphere meets continental lithosphere the oceanic lithosphere is sub ducted and a volcanic mountain belt is formed and the continental margin o Continent Continent Convergence Where two continents converge the crust crumples and thickens creating high mounts and a wide plateau Himalayas Transform Fault Boundaries o Continental Transform Fault Plates slip horizontally past each other San Andres fault o Mid Ocean Ridge Transform Fault Mid Ocean ridges are typically offset by transform faults Eurasian plate Suggested Video Secrets in Stone o The role of paleomagnetism in the evolution of plate tectonic theory o http online wr usgs gov calendar 2004 jul04 html Seafloor As a Magnetic Recorder Produced by the convection of the liquid Fe Ni alloy in the outer core Similar to the ones produced by a