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What is the theory of continental drift ?

What is the theory of continental drift ?. the idea that the continents were once all joined together in one super-continent called Pangaea and slowly moved to their current positions. Alfred Wegener. Continental drift- alfred wegener. Evidence of “continental drift”— .

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What is the theory of continental drift ?

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  1. What is the theory of continental drift? • the idea that the continents were once all joined together in one super-continent called Pangaea and slowly moved to their current positions

  2. Alfred Wegener Continental drift- alfredwegener

  3. Evidence of “continental drift”— • . • Physical fit of continents • Fossil evidence • Rock layer sequences • Glacial evidence • Coal Deposits in Antarctic Alfred Wegener Proposed theory 1912

  4. Shoreline Fit of the Continents http://www.abdn.ac.uk/zoohons/lecture1/img008.GIF

  5. Fossil Evidence The fossils from the exact same animals are found on continents separated by vast oceans.

  6. A Palm tree preserved in the cliffs of Nova Scotia Canada.

  7. Matching Rock Layers Matching Mountain Ranges

  8. Glacier Evidence Glaciers scars are found on continents which are today too warm for glaciers.

  9. Alfred Wegener Continental drift- alfredwegener

  10. HARRY HESS AND THE GLOMAR CHALLENGER

  11. Sediment gets older towards the edges of continents

  12. Magnetism

  13. Evidence of Sea Floor Spreading • Radiometric Dating • Older rocks further from ridges • Sediment Samples • Sediment layers thicker further away from ridges • Rheology • Higher temps @ ridges • Magnetic Anomalies • Poles reverse, magnetic minerals frozen in place as rock cools and hardens • Direct measurements of plate movement

  14. If wegeneronly knew

  15. Outer layer 5-100 km thick 2 types of crust Oceanic (very dense, made of basalt) Continental (less dense, made of granite) The Crust

  16. Convection currents move the plates Watch Convection Currents of Magma Move the Tectonic Plates

  17. What landforms are associated with a diverging plate boundary between two ocean plates?

  18. MID-OCEAN RIDGE

  19. What land forms are associated with a transforming plate boundary between two continental plates?

  20. EARTHQUAKES

  21. FAULT LINES

  22. What land forms are associated with a converging plate boundary between a continental plate and an oceanic plate?

  23. TRENCH, VOLCANOES OR MOUNTAINS

  24. TRENCHES

  25. http://www.thirteen.org/savageearth/hellscrust/assets/images/ringoffire.jpghttp://www.thirteen.org/savageearth/hellscrust/assets/images/ringoffire.jpg

  26. What landform(s) are associated with converging boundary between two continental plates?

  27. Mountains

  28. What landform(s) are associated with converging boundary of two oceanic plates?

  29. Trench and Island Arc

  30. Aleutian Islands

  31. Japan and Mariana Trench

  32. HOT SPOTS Tectonic plate moves slowly over the Hot Spot

  33. SONAR = Sound Navigating and Ranging • Developed early 1900’s • Originally – detect icebergs • WWI – detect submarines • After WWII – map seafloor • Revealed features of seafloor in great detail – new to scientists! So, how do we know what’s on the seafloor?

  34. Depth = ½ x Velocity x Time If sonar takes 100 seconds to return….how deep is the water? D = ½ x 1500 m/s x 100 seconds D = 75,000 meters deep

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