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Plate Tectonics A scientific revolution begins
Continental drift and paleomagnetism <ul><li>Renewed interest in continental drift initially came from rock magnetism   </...
Continental drift and paleomagnetism <ul><li>Polar wandering </li></ul><ul><ul><ul><li>The apparent movement of the magnet...
Continental drift and paleomagnetism <ul><li>Polar wandering </li></ul><ul><ul><ul><li>Curves for North America and Europe...
Polar-wandering paths for Eurasia and North America Figure 2.11
A scientific revolution begins <ul><li>During the 1950s and 1960s technological strides permitted extensive mapping of the...
Seafloor spreading occurs along the oceanic ridges
A scientific revolution begins <ul><li>Geomagnetic reversals </li></ul><ul><ul><ul><li>Geomagnetic reversals are recorded ...
Paleomagnetic reversals recorded in oceanic crust Figure 2.16
A scientific revolution begins <ul><li>Geomagnetic reversal </li></ul><ul><ul><ul><li>Paleomagnetism  was the most convinc...
Plate tectonics:  The  new paradigm <ul><li>Earth’s major plates   </li></ul><ul><ul><ul><li>Associated with Earth's stron...
Plate tectonics:  The  new paradigm <ul><li>Earth’s major plates </li></ul><ul><ul><ul><li>Seven major lithospheric plates...
Earth’s plates Figure 2.19 (left side)
Earth’s plates Figure 2.19 (right side)
Plate tectonics:  The  new paradigm <ul><li>Earth’s major plates </li></ul><ul><ul><ul><li>Plates move relative to each ot...
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C:\Users\Lisa Knight\Desktop\A Scientific Revolution Begins

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C:\Users\Lisa Knight\Desktop\A Scientific Revolution Begins

  1. 1. Plate Tectonics A scientific revolution begins
  2. 2. Continental drift and paleomagnetism <ul><li>Renewed interest in continental drift initially came from rock magnetism </li></ul><ul><li>Magnetized minerals in rocks </li></ul><ul><ul><ul><li>Show the direction to Earth’s magnetic poles </li></ul></ul></ul><ul><ul><ul><li>Provide a means of determining their latitude of origin </li></ul></ul></ul>
  3. 3. Continental drift and paleomagnetism <ul><li>Polar wandering </li></ul><ul><ul><ul><li>The apparent movement of the magnetic poles illustrated in magnetized rocks indicates that the continents have moved </li></ul></ul></ul><ul><ul><ul><li>Indicates Europe was much closer to the equator when coal-producing swamps existed </li></ul></ul></ul>
  4. 4. Continental drift and paleomagnetism <ul><li>Polar wandering </li></ul><ul><ul><ul><li>Curves for North America and Europe have similar paths but are separated by about 24  of longitude </li></ul></ul></ul><ul><ul><ul><ul><li>Differences between the paths can be reconciled if the continents are placed next to one another </li></ul></ul></ul></ul>
  5. 5. Polar-wandering paths for Eurasia and North America Figure 2.11
  6. 6. A scientific revolution begins <ul><li>During the 1950s and 1960s technological strides permitted extensive mapping of the ocean floor </li></ul><ul><li>Seafloor spreading hypothesis was proposed by Harry Hess in the early 1960s </li></ul>
  7. 7. Seafloor spreading occurs along the oceanic ridges
  8. 8. A scientific revolution begins <ul><li>Geomagnetic reversals </li></ul><ul><ul><ul><li>Geomagnetic reversals are recorded in the ocean crust </li></ul></ul></ul><ul><ul><ul><li>In 1963 Vine and Matthews tied the discovery of magnetic stripes in the ocean crust near ridges to Hess’s concept of seafloor spreading </li></ul></ul></ul>
  9. 9. Paleomagnetic reversals recorded in oceanic crust Figure 2.16
  10. 10. A scientific revolution begins <ul><li>Geomagnetic reversal </li></ul><ul><ul><ul><li>Paleomagnetism was the most convincing evidence set forth to support the concepts of continental drift and seafloor spreading </li></ul></ul></ul>
  11. 11. Plate tectonics: The new paradigm <ul><li>Earth’s major plates </li></ul><ul><ul><ul><li>Associated with Earth's strong, rigid outer layer </li></ul></ul></ul><ul><ul><ul><ul><li>Known as the lithosphere </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Consists of uppermost mantle and overlying crust </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Overlies a weaker region in the mantle called the asthenosphere </li></ul></ul></ul></ul>
  12. 12. Plate tectonics: The new paradigm <ul><li>Earth’s major plates </li></ul><ul><ul><ul><li>Seven major lithospheric plates </li></ul></ul></ul><ul><ul><ul><li>Plates are in motion and continually changing in shape and size </li></ul></ul></ul><ul><ul><ul><li>Largest plate is the Pacific plate </li></ul></ul></ul><ul><ul><ul><li>Several plates include an entire continent plus a large area of seafloor </li></ul></ul></ul>
  13. 13. Earth’s plates Figure 2.19 (left side)
  14. 14. Earth’s plates Figure 2.19 (right side)
  15. 15. Plate tectonics: The new paradigm <ul><li>Earth’s major plates </li></ul><ul><ul><ul><li>Plates move relative to each other at a very slow but continuous rate </li></ul></ul></ul><ul><ul><ul><ul><li>About 5 centimeters (2 inches) per year </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Cooler , denser slabs of oceanic lithosphere descend into the mantle </li></ul></ul></ul></ul>

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