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Formation of the Earth

Formation of the Earth. Previous Theories. Continental Drift Theory Developed by Alfred Wegner (1900’s) Believed continents were once all combined into one landmass he called Pangaea meaning “All Earth” Continents seemed to fit together like a jigsaw puzzle

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Formation of the Earth

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  1. Formation of the Earth

  2. Previous Theories • Continental Drift Theory • Developed by Alfred Wegner (1900’s) • Believed continents were once all combined into one landmass he called Pangaea meaning “All Earth” • Continents seemed to fit together like a jigsaw puzzle • Explained why fossils of the same plants and animals are found on the coast of Africa and South America

  3. Pangaea

  4. More Theories • Sea Floor Spreading (1950’s) • Cracks in the ocean floor spread apart allowing magma to rise and create new ocean crust • This helped explain underwater mountain ridges that were found at the bottom of oceans

  5. Mapping the World’s Oceans

  6. Plate Tectonics • Current theory of earth formation (1960’s) • Lithosphere is divided in plates that move along the magma of the asthenosphere • Scientists don’t know exactly what causes the plates to move

  7. Possible Forces that Cause Plate Movement • Ridge Push – gravity causes the oceanic lithosphere to sink into the asthenosphere

  8. Ridge Push

  9. Possible Forces that Cause Plate Movement • Slab pull - because the oceanic lithosphere is denser than the asthenosphere the edge sinks and pulls the rest of the tectonic plate with it

  10. Slab Pull

  11. Possible Forces that Cause Plate Movement • Convection – hot rock deep in the Earth rises while cooler rock sinks, which causes the oceanic lithosphere to move sideways away from the oceanic ridge

  12. Convection

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