Keweenawan Supergroup

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]

  1. ^ Cite error: The named reference N505 was invoked but never defined (see the help page).
  2. ^ "Geologic Unit: Keweenawan". GEOLEX Database. United States Geological Survey. Retrieved June 20, 2012.
  3. ^ "Geology of the Porcupine Mountains" (PDF). Michigan Department of Natural Resources. p. 1. Archived from the original (PDF) on January 18, 2012. Retrieved June 19, 2012.