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Unformatted text preview: Ch.2 - Plate Tectonics Key Figures : changed the way we look at the Earth Alfred Wegener J. Tuzo Wilson Harry Hess Antonio Snider-Pellegrini : 1858 he looked at maps and saw they seemed to fit together Continental Drift : the hypothesis that continents are mobile Proposed by German meteorologist, Alfred Wegener He published The Origins of Oceans and Continents in 1915 he hypothesised a former super continent, Pangaea idea was founded on strong evidence - fit of continents- location of glaciations- fossil organisms - rock type and structural similarities - paleoclimates preserved in rocks Wegeners idea was debated and ridiculed- most scientists didnt believe him- lack of a mechanism for drift a major criticism Wegener died in 1930 at age of 40 lacking an advocate, the drift hypothesis faded the idea was revived in the 1950s Continental Fit : Wegener noted that continents seemed to fit together he argued the fit could not be coincidental present shorelines make a rough fit the continental shelf edges make a better fit Glacial Evidence : Permian glacial till is found on 4 continents the tills in Africa and India are now near the equator A cooler earth? No. Permian tropical plants are known Paleoclimactic Evidence : Placing Pangaea over the Permian South Pole He correctly predicted where to find:- tropical coals- tropical reefs- subtropical deserts - subtropical evaporites Fossil Evidence : Identical fossils found on widely separated landmasses- Mesosaurus : freshwater reptile found in Africa and South America - Glossopteris : subpolar plant with heavy seeds found on every continent - Lystrosaurus : non-swimming...
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- Spring '08