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PHYS 0106 (Spring, 2001) Earth History Timeline |
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| Phanerozoic Eon: Cenozoic Era: Quaternary Period | |||
Timeline Links Phanerozoic Neoproterozoic Mesoproterozoic Paleoproterozoic Archean Other Links Historical Geology Page Physical Geology Page Mike's Home Page |
Writer/Researcher: Kevin St. Laurent Editor: Brian Melloni Web Page Builder: Kevin St. Laurent The formation of the Great Lake is believed to have been most likely caused by erosion due to water currents. There are a few other theories such as glacial erosion or continental crust movement. Most of those are not as accepted as to how the erosion had taken place. Although many geologists still will not accept the idea that major catastrophes could have ever occurred, it is the main idea behind the formation of the Great Lakes.
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The idea of the water current erosion starts with regular erosion of the land. This is what is called denudation of the Canadian Shield. The catastrophic currents that swept across the North American continent, forced into motion by uplift, caused this. The rocks that existed underneath consisted of material such as shale and limestone, which are rocks that are found to be soft, easily changed, and dated back to the Precambrian and the Paleozoic. The continental currents were so fast and they sustained for such a long period of time that they created basement depressions and domes into the soft exposed rock. Most of the deposits were carried away to the South, redeposited on the coast or just off the coast onto the continental shelf. These large gapping holes that were left over were filled in with some of the current water and the rest with rain deposited water. Thus, the Great Lakes were formed.