2.  What evidence was used to support the continental drift hypothesis?  What was one of the main objections to the continental drift hypothesis?  What is the theory of plate tectonics?  In what major way does the plate tectonics theory depart from the continental drift hypothesis?

3.  What are the three types of plate boundaries?  Where does new lithosphere form?  How do mountain systems such as the Himalayas form?  What type of plate motion occurs along a transform fault boundary?

4.  What evidence is used to support the plate tectonics theory?  What are the major driving forces for plate tectonics?  What models have been proposed to explain the driving mechanism for plate motion?

9. Pangaea Continental Drift Hypothesis

10. Gondwana

11.  Began in early Mesozoic (~200 mya)  Evidence  Continental jigsaw puzzle  Fossil distribution  Rock types & geologic features  Ancient climates

18. Location of the fossil site at the Oliver Bluffs on the Beardmore Glacier

19.  There are rock formations (such as mountain ranges) on different continents that match up beautifully when the continents are put back together.

21.  Paleoclimatic data  Extreme global cooling?  Wegener’s explanation

26.  What mechanism allows movement?  Not all evidence supported the hypothesis.  Some thought the idea was intriguing or an answer to a previously unexplained phenomena.

29.  1968; more encompassing than CDH  Lithosphere broken into plates, slide over asthenosphere

31.  LARGE – 94% of Earth’s S.A.  North American  South American  Pacific  African  Eurasian  Australian-Indian  Antarctic

32.  INTERMEDIATE – mostly oceanic  Caribbean  Nazca  Phillipine  Arabian  Cocos  Scotia  Juan de Fuca

33.  Divergent (constructive)  Convergent (destructive)  Transform (conservative)

37.  Plate boundaries  Types of plate boundaries  Transform fault boundaries  Plates slide past one another  No new crust is created or destroyed  Transform faults  Most join two segments of a mid-ocean ridge  Aid the movement of oceanic crustal material

38.  Evidence from ocean drilling  Some of the most convincing evidence confirming seafloor spreading has come from drilling directly into ocean-floor sediment  Age of deepest sediments  Thickness of ocean-floor sediments verifies seafloor spreading

39.  Hot spots and mantle plumes  Caused by rising plumes of mantle material  Volcanoes can form over them (Hawaiian Island chain)  Mantle plumes  Long-lived structures  Some originate at great depth, perhaps at the mantle- core boundary

41.  Evidence for the plate tectonics model  Paleomagnetism  Probably the most persuasive evidence  Ancient magnetism preserved in rocks  Paleomagnetic records show  Polar wandering (evidence that continents moved)  Earth’s magnetic field reversals  Recorded in rocks as they form at oceanic ridges

44.  Measuring plate motion  By using hot spot “tracks” like those of the Hawaiian Island – Emperor Seamount chain  Using space-age technology to directly measure the relative motion of plates  Very Long Baseline Interferometry (VLBI)  Global Positioning System (GPS)

46.  Driving mechanism of plate tectonics  No one model explains all facets of plate tectonics  Earth’s heat is the driving force  Several models have been proposed  Slab-pull and ridge-push model  Descending oceanic crust pulls the plate  Elevated ridge system pushes the plate

48.  Several models have been proposed  Plate-mantle convection  Mantle plumes extend from mantle-core boundary and cause convection within the mantle  Models  Layering at 660 kilometers  Whole-mantle convection

51.  Present-day motions have been extrapolated into the future some 50 million years  Areas west of the San Andreas Fault slide northward past the North American plate  Africa collides with Eurasia, closing the Mediterranean and initiating mountain building  Australia and New Guinea are on a collision course with Asia

53. End of Chapter 7