Mysterious Midcontinent Rift is a geological hybrid

16 octubre 2014

Geologists have a new explanation for the formation of the Midcontinent Rift, an ancient 2,000-mile-long underground crack that starts in Lake Superior and runs south. The rift is a geological hybrid, having formed in three stages: it started as an enormous narrow crack in the Earth’s crust; that space then filled with an unusually large amount of volcanic rock; and, finally, the igneous rocks were forced to the surface, forming some of the Upper Midwest’s beautiful scenery.