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Explore the theory of continental drift, Pangea, and plate tectonics. Learn about Wegener's rejected theory, supporting evidence, and the Earth's core heat source. Follow along with a hands-on activity to assemble Pangaea.

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  1. Add to Table of Contents Pangea Pg. 18 Continental Drift Pg. 19

  2. How old is the Earth? • 4.6 billion years old

  3. Fossils of the dinosaur, Cryolophosaurus were discovered in Antarctica in 1991. The picture shows the environment that the dinosaur lived in. • How do you explain the difference between the Antarctic of the past and of the present? Antarctic of today

  4. Continental Drift Pg. 19 • In 1912, Alfred Wegener suggested the theoryof continental drift: continents once formed a single landmass(Pangaea), then broke apart and drifted to where they are today. • Pangaea means all land.

  5. What happened to Pangea? • Over time, Pangea began to break apart to what we currently see today.

  6. Asia Pangaea Laurasia N. America, Europe Gonwanaland Africa S. America Antarctica Australia (India)

  7. Evidence to support continental drift: 1. Shapes of the continents look like they fit together.

  8. 2. The same species of fossils are found on different continents. Example: Mesosaurus (a reptile) was found in South America and Africa (it couldn’t swim that far, so there had to be a shallow sea between these countries – not a huge ocean!-or they were connected at one time.

  9. 3. There are similar rock types, ages and structures found on different continents. (Ex: Appalachian Mountains in N. America match up with ranges in Greenland, Scotland and Northern Europe. Mts. in Eastern S. America match with those in Western Africa. Before After

  10. 4. Ancient climates – glacial evidence in warm environments, tropical plant and animal fossils found in cold environments. (Ex: -glacier evidence)

  11. Why was Wegener’s theory rejected? • Wegener’s theory was rejected because he couldn’t provide a mechanism for movement. • He suggested the tides caused continents to plow through the rock of the ocean floor, but that was disproven by no scarring on the sea floor and no debris.

  12. How was it determined that the theory of continental drift was possible? Harry Hess a geologist studied Mid-Ocean Ridges during WWII while looking for submarines.

  13. Sea-Floor Spreading - Magma rises to the surface, solidifies, new crust forms and pushes older crust farther away from the ridge.

  14. Sea Floor Spreading Animation

  15. Harry Hess suggested sea-floor spreading at ocean ridges gave proof for continental drift. A. The rock closer to the ridges is younger than the rock far from the ridges. B. Oceanic rock is much younger than continental rock. C. Magnetic patterns in sea floor rock support this.

  16. Assignment: • 1. Cut out continents. • 2. Assemble them into Pangaea. • Use fossil evidence, Mountains, glacial and mineral deposits to help you assemble Pangaea. • 3. Glue on page 18.

  17. Thru 1: pg. 31Please copy this concept map and then complete it by filling in one appropriate descriptor at the end of each arrow. Use pages 239-241 in the textbook. When discovered Scientist Definition Theory of Continental Drift Supporting Evidence What is missing? Rock Formations Climatic Continents Fossils

  18. As you travel towards the center of the Earth, the temperature increases because of heat generated by the core. Before reading: What makes the heat at the Earth’s core?

  19. Don’t write! Why is the core so hot? • It's a combination of radioactivity (the radioactive materials in the Earth generate heat) and the residual heat from the formation of the Earth. When all of the matter that created the Earth fell together, it picked up kinetic energy falling in. When it stopped at the proto-Earth, the kinetic energy was turned into heat. The Earth hasn't cooled yet. But, the vast majority of the heat in Earth's interior—up to 90 percent—is fueled by the decaying of radioactive isotopes like Potassium 40, Uranium 238, 235, and Thorium 232 contained within the mantle. These isotopes radiate heat as they shed excess energy and move toward stability. "The amount of heat caused by this radiation is almost the same as the total heat measured emanating from the Earth." Read more at: http://phys.org/news62952904.html#jCp

  20. Add to Table of Contents: • Boundaries Draw-Along Pg. 56 • Plate Tectonics Pg. 57

  21. Don’t write-Review • Prior to Alfred Wegener’s theory of continental drift geologists thought continents were fixed in their locations. In developing his theory which of the following evidence was NOT used by Wegener? • Fossil similarities between southern continents. • Evidence of polarity change in found along the Mid-Atlantic Ridge. • Similarities in the paleoclimates of South America and Africa. • The apparent fact the South America and Africa seemed to fit together.

  22. Plate Tectonics Pg. 57 Lithosphere - the rigid outer layer of the Earth. • Made of the crust and the solid outer layer of mantle. Asthenosphere - the layer of “plastic” rock in the lower mantle. • Flows like a very thick liquid.

  23. Lithospheric Plates • Lithospheric Plates-The rigid lithosphere is broken into plates =tectonic plates • Float on the semi rigid, moving asthenosphere.

  24. Theory of Plate Tectonics – explains how the lithospheric plates move and change shape.

  25. Tectonic Plates

  26. Earth’s lithosphere is broken into 7 major(large) plates and numerous minor (smaller) ones. • The plates glide over the asthenosphere and produce earthquakes, volcanoes and create mountains.

  27. Convection Currents - driving forces of plate tectonics - very hot material at the deepest part of the mantle rises, then cools and sinks again, then repeating. This cycle is repeated over and over. ***Remember…this heat is generated by the core!! HOT!!!!

  28. How Plate Tectonic Works As magma heats up and rises, it exits through the rift in the middle of the mid-ocean ridge. It cools and pushes the plates apart. The Asthenosphere is also moving in convection currents(created by unequal heating), carrying the plates outward.

  29. What is the average rate of movement from lithospheric plates? • 5cm/yr (2inches) and it is driven by unequal heating of the Earth.

  30. Plate Boundaries 1. Convergent – moving together 2. Divergent – moving apart 3. Transform – moving side by side

  31. Convergent Boundary – Oceanic & Oceanic Note – plates are reversed http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

  32. Aleutian Islands, Alaska, May 23, 2006

  33. Convergent Boundaries Continental - Continental http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

  34. Himalayan Mountains

  35. Convergent Boundary – Oceanic & Continental http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

  36. Mt. St. Helen – Cascade Mtns.May 20, 1980

  37. Divergent boundary – Continental - Continental

  38. Divergent Boundary – Arabian and African Plates Arabian Plate Red Sea African Plate

  39. Divergent BoundaryOceanic - Oceanic

  40. Transform Boundary – San Andreas Fault www.geology.com

  41. San Andreas Fault

  42. Train crossing San Andreas Fault – Cajon Pass, CA

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