_4-PlateTectonics_4Sept08

_4-PlateTectonics_4Sept08 - Georgia Aquarium, Atlanta...

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Unformatted text preview: Georgia Aquarium, Atlanta QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture. Sea Stories - the State of the Ocean as told by those that live there QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture. Global Tectonics: Plates and Plumes Why study plates and their motions? Why 12.1 How does continental drift relate to plate tectonics? 12.2 What is the evidence that plates are rigid? 12.3 What is the evidence that plates move apart at divergent 12.3 plate boundaries? plate 12.4 What is the evidence that subduction occurs at convergent 12.4 plate boundaries? plate 12.5 What is the evidence that plates slide past one another at 12.5 transform plate boundaries? transform 12.6 What does the mantle-plume hypothesis explain that plate 12.6 tectonics cannot explain? tectonics 12.7 How do we know ... that plates move in real time? 12.8 What forces cause plate motions and plumes? 12.9 What were the consequences of plate motion over 12.9 geologic time? geologic Why study plates and their motions? 12.1 How does continental drift relate to plate tectonics? 12.1 12.2 What is the evidence that plates are rigid? 12.3 What is the evidence that plates move apart at divergent 12.3 plate boundaries? plate 12.4 What is the evidence that subduction occurs at convergent 12.4 plate boundaries? plate 12.5 What is the evidence that plates slide past one another at 12.5 transform plate boundaries? transform 12.6 What does the mantle-plume hypothesis explain that plate 12.6 tectonics cannot explain? tectonics 12.7 How do we know ... that plates move in real time? 12.8 What forces cause plate motions and plumes? 12.9 What were the consequences of plate motion over 12.9 geologic time? geologic Why study plates and their motions? 12.1 How does continental drift relate to plate tectonics? 12.1 12.2 What is the evidence that plates are rigid? 12.3 What is the evidence that plates move apart at divergent 12.3 plate boundaries? plate 12.4 What is the evidence that subduction occurs at convergent 12.4 plate boundaries? plate 12.5 What is the evidence that plates slide past one another at 12.5 transform plate boundaries? transform 12.6 What does the mantle-plume hypothesis explain that plate 12.6 tectonics cannot explain? tectonics 12.7 How do we know ... that plates move in real time? 12.8 What forces cause plate motions and plumes? 12.9 What were the consequences of plate motion over 12.9 geologic time? geologic Why study plates and their motions? If you are 20 years old and born in the U.S., your birthplace is about 1 meter farther from Europe than it was on the day you were born. Europe This speed (~ the rate of fingernail growth) This seems sluggish, but bear in mind the mass of the lithospheric plates that are moving and the forces required to accomplish it. forces My goal is to broaden your understanding of My these large, yet fundamental, Earth forces. these Why study plates and their motions? Objectives of these lectures: Objectives – llearn how geoscientists know that lithospheric earn plates move. plates – gain an explanation as to why plates move. – know what happens at plate boundaries and know explain why it happens. explain – evaluate the implications of plate motions for evaluate Earth’s history. – llearn the origins of geologic features not explained earn by plate tectonics. by How does continental drift relate to plate tectonics? tectonics? Alfred Wegener – advocated matching Alfred continental boundaries by shape and geologic features (1912, 1928). Hypothesized idea of continental drift—that continents move over geologic time. geologic – Good data on fitting continents together – However, no good mechanism for movement Posited them moving like icebreakers through the Posited oceanic crust Idea dismissed by most of the geologic community Idea How does continental drift relate to plate tectonics? tectonics? Wegener saw the continents as a jigsaw puzzle that fit together into a prior single continent, Pangea. Fig 11.2 How does continental drift relate to plate tectonics? tectonics? Alfred Wegener – advocated matching Alfred continental boundaries by shape and geologic features (1912, 1928). Hypothesized idea of continental drift—that continents move over geologic time. geologic – Good data on fitting continents together – However, no good mechanism for movement Posited them moving like icebreakers through the Posited oceanic crust Idea dismissed by most of the geologic community Idea QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture. How does continental drift relate to plate tectonics? tectonics? The continental drift hypothesis, the forerunner The of plate tectonics, proposed that all landmasses were joined in a supercontinent called Pangea. Pangea broke into continental fragments that drifted into their current positions. positions. The continental drift hypothesis was not The universally accepted because it lacked a reasonable explanation for why continents moved. In the plate tectonic theory, continents are like passengers on the plates. are One of the things Wegener didn’t know One Lava Pool, Erta Ale, Ethiopia QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture. What is the evidence for rigid plates? What The Earth’s lithospheric plates ...
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