U of Minnesota Press, 1982 - 255 pages
Have you ever wondered how the Mississippi River was formed? Or why shark teeth have been found in the Iron Range of the Upper Midwest? Towering mountain ranges, explosive volcanoes, expansive glaciers, and long-extinct forms of both land and sea life were an important part of Minnesota's ancient history. Today the evidence of this remarkable heritage is revealed in the state's rocky outcroppings, stony soils, and thousands of lakes.
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Minnesotas Place in Geologic History
Early Precambrian Time 4500 to 2500 Million Years Ago
Middle Precambrian Time 2500 to 1600 Million Years Ago
Late Precambrian Time 1600 to 600 Million Years Ago
PostPrecambrian Time 600 to 2 Million Years Ago
The Quaternary Period 2 Million Years Ago to the Present
Nonmetals Fuels and Water
abundant basalt basin Batholith bedrock beds belts beneath Cambrian carbonate Chapter contain Cretaceous crust deposits dikes dolomite Duluth Complex earth eroded erosion exposed fault Figure Fond du Lac formed fossils gabbro geologists Glacial Lake Glacial Lake Duluth glacier gneisses grains granite gravel greenstone Highway indicate iron iron-formation kilometers Lake Agassiz Lake Superior Lake Vermilion lava flows layers limestone located magma margins melting meltwater Mesabi Range metamorphic Middle Precambrian million years ago minerals mining Minnesota Geological Survey Minnesota River Minnesota River Valley Mississippi River Moines Lobe Moraine North America North Shore º º Ordovician outcrops Paleozoic Park Plate Precambrian Precambrian rocks probably quarry quartz Rainy Lake River Warren roadcut rock types rock units sand sandstone sedimentary rocks sediments shale Soudan southeastern Minnesota streams Superior Lobe surface taconite thick Thomson Formation uranium Vermilion district weathering Wisconsin zone