mellowyellow
Well-known Member
May 17, 2021
Photographer: Rod Benson
These light-colored cliffs are made of nearly vertical layers of Madison limestone, formed from sediment deposited during the Mississippian Period about 340 million years ago. Thick deposits of corals, shells, and other forms of calcium carbonate accumulated on the floor of a shallow tropical sea when this part of Earth’s crust was much closer to the equator. The hiker in the blue shirt provides a sense of scale.