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The Midcontinent Rift System (MRS) or Keweenawan Rift is a 2,000 km (1,200 mi) long geological rift in the center of the North American continent and south-central part of the North American plate. It formed when the continent's core, the North American craton , began to split apart during the Mesoproterozoic era of the Precambrian , about 1.1 ...
Iowa magnetic anomaly map showing the Midcontinent Rift curving from the north center to the southwest part of the state. [8]Buried deeply within Iowa's bedrock, the Midcontinent Rift System can be seen clearly in magnetic anomaly maps of Iowa.
On a map showing only volcanic rocks, the west coast of North America shows a striking continuous north–south structure, the American Cordillera. The North American Cordillera extends up and down the coast of North America and roughly from the Great Plains westward to the Pacific Ocean , narrowing somewhat from north to south.
The Keweenawan Supergroup is a supergroup of volcanic and sedimentary rocks that fill the Midcontinent Rift System in the U.S. states of Michigan, Wisconsin, and Minnesota. [1] [2] It is about 30 kilometers (19 mi) thick and it formed about 1.1 billion years ago. [3]
[4]: 7 This zone of crustal thinning and fracturing is the Midcontinent Rift System; it extends in a boomerang shape for over 2,200 km (1,400 mi) from northeastern Kansas northward through Iowa, under the Twin Cities of Minnesota, beneath Lake Superior, and then south through the eastern Upper Peninsula of Michigan and beneath the central Lower ...
The craton started to rift about 1.1 Ga, and the fissure (now the Midcontinent Rift System) ... Map and aerial photos. North America map; Physical map;
The Midcontinent Rift System in North America is marked by a series of horsts extending from Lake Superior to Kansas. [12] The Rwenzori Mountains in the East African Rift are an upthrown fault block, and are the highest non-volcanic, non-orogenic mountains in the world. [13] [14]
Although not directly impacting the current boundaries of Missouri, the Midcontinent Rift System formed from 1.2 to one billion years ago as mafic lava erupted in a rift zone spanning Lake Superior through Iowa to Kansas.