EARTH121 Chapter Notes - Chapter 12: Seafloor Spreading, Mid-Ocean Ridge, Continental Drift
29 Aug 2016
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Changes in the past positions of continents and ocean basins. The origins of mountain belts and seamount chains. Earth is broken, and it is rigid, but there is motion. Continental drift: earth is continuously changing continents move, split apart, and recombine, ocean basins open and close however, strong resistance: what"s great enough to move continents . Evidence: arctic mass, animal fossils, rock/mountain chains, plant fossils reflect climate (paleoclimactic) Still couldn"t explain how or why continents moved. More sea floor mapping (bathymetry) under water in the period of wwii sonar. During the 1950s and 1960s, the ocean floor was mapped and the global oceanic ridge system was discovered. Great tensional forces,high heat flow, volcanism near the mid-atlantic ridge. Ocean floor was younger than the age of the earth (180 million years) Ocean ridges are located above zones of upwelling in the mantle. Seafloor spreads ad carries away older seafloor laterally away from the ridge crest.
