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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 ...
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]
Most of Lake Superior lies within the basin of the Midcontinent Rift. The rocks of Lake Superior's northern shore date back to the early history of the earth. During the Precambrian (between 4.5 billion and 540 million years ago) magma forcing its way to the surface created the intrusive granites of the Canadian Shield. [36]
The buff area on the north margin is the Lake Nipigon area. The rock formations created by the rift included gabbro and granite intrusive rocks and basalt lavas. [4] In the Lake Superior region, the upwelling of this molten rock may have been the result of a hotspot which produced a triple junction. [2] The hotspot domed the rocks of the Lake ...
The Duluth Complex includes much of Minnesota's Arrowhead Region north of Lake Superior.From the west near Duluth, Minnesota, it arcs north and northeast to about 48° north latitude south of Knife Lake, proceeds east at that latitude some five to twenty kilometers distant from and south of the Canada–US border to about 90° west longitude where it joins the border at the Pigeon River, and ...
Map of Minnesota bedrock by age. Shaded relief image: Superior Upland in the northeast, the flat Red River Valley in the northwest, Central Minnesota's irregular landscape, the Coteau des Prairies and Minnesota River in the southwest, and the southeast's dissected Driftless Area along the Mississippi River below its confluences with the Minnesota and St. Croix in East Central Minnesota
The recent discovery of wreckage more than 600 feet deep in Lake Superior solves one mystery of the SS Arlington, a 244-foot bulk carrier that sank in 1940. But another remains.
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.