Lab. 1 Plate Tectonics and General Geography1.History of the plate tectonic theory: Continental Drift: by Alfred Wegner in 1915: Continental configuration of the past were different. Occurrence of identical fossils in geological strata from opposite sides of Atlantic ocean: Africa and South America. Fit them together like a jigsaw, a supercontinent named Pangaea (Pan: entire, Gaea: land) drifted apart about 300 Ma ago (Carboniferous). Evidences: land feature, fossils, climate. Drawback: Fail to provide a convincing driving mechanism .Seafloor Spreading: by Harry Hess in the early 1960s: new oceanic crusts are created in oceanic ridges (e.g. Mid-Atlantic Ridge) and as the process continues, the seafloor is carried in a conveyor belt heading away from the ridge and eventually descends in the vicinity of deep ocean trenches where they meet the continental crusts.2.Earth layers (Page 8 on the lab manual): Chemical: Inner core, outer core, lower mantle, upper mantle, crust; Physical: Lithosphere
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