SCIENCE OF THE RIFT

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SCIENCE OF THE RIFT

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PHOTO



http://www.interstatefalls.org/geology_files/image002.jpg



[EXCERPT]

http://www.interstatefalls.org/geology.htm

The North American continent includes a Midcontinent Rift. This 1200-mile arc-shaped rift extends from Detroit, up through the middle of the Lower Peninsula, across Lake Superior, then down along the Minnesota/Wisconsin border, and across Iowa to eastern Nebraska. This tear in the continent allowed lava to reach the surface of the earth and accumulate in the rift valley as basalt rock 1.1 billion years ago.

A large basalt lava flow flooded this rift valley, bringing what would one day become the Penokee/Gogebic range to the Earth’s surface, 1.1 billion years ago. (That is a very long time ago. What is now Wisconsin and Michigan was located near the equator or even southern hemisphere at the time, on a continent much different from today. This is a time before land plants, fish, or most animal fossils. The above-ground world was in a transition to an oxygenated atmosphere.)