Minnesota's GeologyU 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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Page 3
... crust of the earth ( Figure 1-1 ) . From quarries at Morton huge blocks of rock equally as old are raised by cranes to be loaded and shipped throughout the United States as architectural stone . The im- portance of these rocks to an ...
... crust of the earth ( Figure 1-1 ) . From quarries at Morton huge blocks of rock equally as old are raised by cranes to be loaded and shipped throughout the United States as architectural stone . The im- portance of these rocks to an ...
Page 4
... crust . The rocks of the North Shore , oddly enough , are the common constituents of ocean basins , whereas those exposed at St. Cloud are typically present in most continental rock masses . The fine - grained texture of the North Shore ...
... crust . The rocks of the North Shore , oddly enough , are the common constituents of ocean basins , whereas those exposed at St. Cloud are typically present in most continental rock masses . The fine - grained texture of the North Shore ...
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abundant basalt basin bedrock beds belts beneath Cambrian carbonate contain County Cretaceous Croix crust deposits dikes dolomite Duluth Complex earth eroded erosion exposed fault Figure Fond du Lac formed fossils G. B. Morey gabbro geologic map geologists Geology of Minnesota Glacial Lake Glacial Lake Duluth glaciers gneisses grains granite greenstone Highway iron iron-formation kilometers Lake Agassiz Lake Superior Lake Vermilion lava flows layers limestone Lower Precambrian mafic magma margins Mesabi Range metamorphic Middle Precambrian million years ago minerals mining Minnesota Geological Survey Minnesota River Mississippi River Moines Lobe Moraine nesota North America North Shore northeastern Minnesota Ordovician outcrops P. K. Sims Paleozoic Park Portage Precambrian Precambrian rocks quarry quartz Rainy Lake River Warren roadcut rock types rock units sand Sandstone sedimentary rocks sediments shale Soudan streams Superior Lobe surface taconite thick Thomson Formation uranium Vermilion district volcanic rocks weathering Wisconsin zone