Many North American Indians believe that we have a special relationship with planet earth. To them, the earth is family. We have a sacred responsibility to the planet and to all creatures that live upon her. We are all part of the circle, all part of Mother Earth. They believe we are charged with the sacred duty: we are the keepers of the earth. It is this special relationship with planet earth that provides the basis for many of the Native Americans’ beliefs, and much of their culture and science. It is this relationship that also defines their ideas and practices on how to use and manage our natural resources.
The Cenozoic era comprised the Tertiary and Quaternary periods. The only geologically significant event during this era was the Pleistocene Ice Age, which occurred between 2 million and 8,000 years ago. This final chapter of the geologic history of the Lake Superior region was different from all the preceding events. Several times during the Pleistocene, huge masses of glacial ice many thousand feet thick (some geologists estimate up to 10,000 feet) covered most of the northern half of North America. The glaciers scraped and removed most of the weathered rock that had been accumulating north of the Great Lakes since the withdrawal of the Paleozoic seas some 270 million years earlier. Much of this debris was carried southward, and when the ice melted, was deposited in lower Michigan, Illinois, Wisconsin, Iowa, and southern Minnesota. The combination of glacial erosion and deposition greatly altered the landscape filling some valleys, deepening others and in general modifying the previous drainage patterns. The Great Lakes were formed by glacial erosion, as were many other lakes.
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