Advanced Plate Tectonics

Phosphorites within 45 deg of eq 6 bauxite and

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Unformatted text preview: 4) coal and oil-warm, humid climate 5) phosphorites-within 45 deg of eq 6) bauxite and laterite-tropical, subtropical weathering 7) desert deposits-both warm and cold cond, direction of wind, continental rotation 8) glacial deposits-30 deg from poles OCE 661 OCE 661 Wegener -> a continental ice sheet covered parts of South America, southern Africa, India and southern Australia about 300 million years ago. Glacial striations on rocks show that glaciers moved from Africa toward the Atlantic Ocean and from the Atlantic Ocean onto South America. Such glaciation is most likely if the Atlantic Ocean were missing and the continents joined OCE 661 Mechanism for continental drifting? (in Wegener’s hypothesis) 1. continental crust plows through oceanic crust like an icebreaker through ice (pole-fleeing force-movement of continents toward Equator) -continental crust is too weak to do this (2.7g/cm3 vs 3.3g/cm3); the force is several millions times smaller than force of gravity) 2. Centrifugal (rotational) and tidal forces are responsible for movement of land masses (westward movement of continents) - tidal forces are too weak to do this OCE 661 Alexander Du Toit, Professor of Geology at Johannesburg University proposed that Pangaea first broke into two large continental landmasses, Laurasia in the northern hemisphere and Gondwanaland in the southern hemisph...
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