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Plate Tectonics

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Presentation on theme: "Plate Tectonics"— Presentation transcript:

1 Plate Tectonics http://geology.csupomona.edu/drjessey/class/Gsc101/Plate.html

2 Continental Drift Alfred Wegener first proposes Continental Drift in his book published in 1915. Suggests that 200 million years ago there existed one large super continent which he called Pangaea (All Land).

3 Continental Drift-evidence 1.Fit of the Continents - Noted the similarity in the coastlines of North and South America and Europe and Africa. Today the fit is done at the continental shelf and it is nearly a perfect match.

4 2. Fossil Similarities 1.Mesosaurus, reptile similar to modern alligator which lived in shallow waters of South America and Africa

5 3. Rock Similarities a.Rocks of same age juxtaposed across ocean basins.

6 b. Termination of mountain chains.

7 4. Paleoclimatic Evidence a.Glacial deposits at equator b.Coral reefs in Antarctica http://www.scotese.com/paleocli.htm

8 The theory dies- Idea was rejected by North American geologists because Wegener couldn't come up with a mechanism for continental drift. Suggested tidal forces, but physicists showed this to be impossible. Wegener dies in 1930 and his idea dies with him.

9 The Plate Tectonic Theory: The Earth's surface is covered by a series of crustal plates. The ocean floors are continually, moving, spreading from the center, sinking at the edges, and being regenerated. Convection currents beneath the plates move the crustal plates in different directions. The source of heat driving the convection currents is radioactivity deep in the Earths core.


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