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The Lake Superior agate is a type of agate stained by iron and found on the shores of Lake Superior. Its wide distribution and iron-rich bands of color reflect the gemstone's geologic history in Minnesota, Wisconsin, Nebraska, Iowa, Kansas, and Michigan. In 1969 the Lake Superior agate was designated by the Minnesota Legislature as the official ...
Jacobsville Sandstone is a red sandstone formation, marked with light-colored streaks and spots, primarily found in northern Upper Michigan, portions of Ontario, and under much of Lake Superior. Desired for its durability and aesthetics, the sandstone was used as an architectural building stone in both Canada and the United States.
Chlorastrolite occurs as amygdaloid structures and fracture fillings in basalt, and when the water and wave action has worn away the basalt, they are found as beach pebbles and granules in loose sediments. It is found in the Keweenaw Peninsula of the Upper Peninsula of Michigan and Isle Royale in Lake Superior. Isle Royale is a National Park ...
The Grand Sable Dunes today form a five-mile-long sand slope that rises from Lake Superior at a 35° angle. The summits of the tallest dunes are as high as 275 feet (85 m) above lake level. Glacial melt during the last major advance/retreat called the Marquette Readvance created the conditions for the formation of the Grand Sable Banks.
The Gunflint chert (1.88 Ga [1]) is a sequence of banded iron formation rocks that are exposed in the Gunflint Range of northern Minnesota and northwestern Ontario along the north shore of Lake Superior. The Gunflint Chert is of paleontological significance, as it contains evidence of microbial life from the Paleoproterozoic. [2]
Government-funded studies have found no adverse health effects from drinking Lake Superior water. [6] [7] A 2003 study of taconite miners concluded that the most likely cause of 14 of the 17 cases of mesothelioma among miners on the iron range was contact with asbestos. Since that study was concluded, 35 more Iron Range miners have been ...
Lake Superior is part of the Midcontinent Rift System, a 1,800 mile scar that formed more than 1 billion years ago where North America started to tear apart.The rift stretches from Kansas up to ...
Carbon-14 testing of wood remains found in sockets of copper artifacts indicates that they are at least 6500 years old. [11] [12] An abandoned copper mine shaft. In Prehistoric Copper Mining in the Lake Superior Region, Drier and Du Temple estimated that over 750,000 tons of copper had been mined from the region. However, David Johnson and ...