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Transcript
The Argument for Continental Drift Alfred L. Wegener Geologist Alfred Wegener noticed similar rocks & fossil remains were found on continents which seemed to fit together He called this “super” continent called Pangaea In 1912 Wegener published the first version & died defending his theory PANGAEA the large landmass that included all of Earth’s present day continents Permian 225 million years ago Triassic 200 million years ago Jurassic 135 million years ago Cretaceous 65 million years ago Present Day CONTINENTAL DRIFT http://www.tectonics.caltech.edu/movi es/outreach/sumatra/pangaea.mov Support for Continental Drift 1. SHAPE OF THE CONTINENTS Continents fit together like puzzle pieces Support for Continental Drift 2. FOSSIL EVIDENCE SAME FOSSILS: DIFFERENT CONTINENTS Mesosaurus was incapable of swimming across a large ocean. Support for Continental Drift 3. ROCK EVIDENCE – Mountain ranges SAME ROCK: DIFFERENT RANGE Existing mountain ranges separated by vast oceans contain rocks of identical mineral content. A prime example are the Appalachian Mountains in the eastern U.S and the Caledonian Mountains in the British Isles. Support for Continental Drift 4. GLACIAL SCARS SAME SCARS: DIFFERENT CONTINENTS Support for Continental Drift 5. LOCATION OF COAL DEPOSITS Coal deposits have been found in temperate and polar regions; however, coal is formed in tropical regions. CONTINENTAL DRIFT IN DOUBT Why didn’t people believe in continental drift? People couldn’t imagine how the earth could be millions of years old People couldn’t imagine a force great enough to move the continents THE TRUTH! North America moves about 1 to 2 centimeters away from Europe every year. The Earth’s Crust The Earth’s crust consists of a number of Plates Plate: large pieces of the crust that moves Plate Tectonics: The interaction of the crustal plates Convergent Convergent = Coming together Over riding plate goes over the top Subducting plate slides underneath Boundry is the area where the two meet Moving Plates Divergent = Moving apart Moving Plates Transform = Moving laterally