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225 Million Years Ago, there was a supercontinent called Pangaea

225 Million Years Ago, there was a supercontinent called Pangaea. Click: Pangea Animation. Crustal Movement. The first theory of crustal movement was introduced in 1915 by Alfred Wegener, and was called The Theory of Continental Drift. 2. :.

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225 Million Years Ago, there was a supercontinent called Pangaea

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  1. 225 Million Years Ago, there was a supercontinent called Pangaea Click: Pangea Animation

  2. Crustal Movement • The first theory of crustal movement was introduced in 1915 by Alfred Wegener, and was called The Theory of Continental Drift 2. : http://www.eoearth.org/files/124901_125000/124947/250px-Wegener3.jpg

  3. Evidence for this Theory • Edges of continents fit together like puzzle pieces • Correlation of rock layers/fossils- Rock layers and fossils found on opposite sides of ocean basins match up • Mountain Chains- Some mountain chains seem to be continuous from continent to continent. • Climateevidence- Ancient climates were different from today. Ex: glacial deposits in tropical regions; coal deposits in Antarctica. • Crustalage- Rocks of the ocean basins are much younger than continental rocks.

  4. Puzzle Pieces that Fit http://pubs.usgs.gov/publications/graphics/apres.gif

  5. FOSSILS http://pubs.usgs.gov/publications/graphics/Fig4.gif

  6. Climate http://volcano.und.nodak.edu/vwdocs/vwlessons/plate_pics/F1.6b.gif

  7. Sea-floor spreading • Sea Floor Spreading: • Theory that states that ocean floors are forming and spreading out from the ridges. • Convection cell: • Driving force for spreading theory. • Hot, molten material from the mantle pushes upward, cools and solidifies at the surface to form new ocean rock. • Currents are created because of density differences in magma.

  8. CONVECTION CURRENTS Click for Convection Cell Animation *10

  9. Click: Video Of Plate Tectonic and Convection Currents

  10. Evidence for Sea Floor Spreading • Igneous Rocks: • Age of rocks increases as distance from ridge increases • Paleomagnetism: • magnetic patterns are symmetrical (the same) on both sides of the spreading centers. As molten ocean rock cools, the magnetic minerals in the rock align themselves with the Earth’s magnetic field. If the magnetic field is opposite what it is today, the minerals will point to the south magnetic pole. The ocean rocks show that during past history, Earth’s magnetic field has reversed a number of times.

  11. PALEOMAGNETISM – Each side of the Mid-Atlantic Ridge shows the same magnetic reversals. Click for Paleomagnetism Animation Click for Paleomagnetism Video

  12. Click: Video: Sea Floor Spreading- Bill Nye

  13. Plate Tectonics • Plate Tectonics: • Theory that Earth’s lithosphere is divided into tectonic plates that move around on top of asthenosphere. Text Pacific Plate is the largest plate http://www.extremescience.com/graphics/platetecmap.gif

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