The story of the geologic formation of the Cave of the Mounds begins with the creation of the rock in which the Cave is found. The Cave was formed within sedimentary rock, a limestone made of compacted seashells. This rock dates back over 400 million years to the Ordovician Period of the earth’s geologic history.
During this Ordovician Period, warm shallow seas covered the continent where we find Wisconsin today. Abundant shell life could thrive in these seas. Layers and layers of calcium carbonate shell debris accumulated and slowly hardened into limestone. Thousands of feet of limestone and other sedimentary rocks were laid down during this Ordovician Period.
Fantastic place to visit!!
more information on their website:
www.caveofthemounds.com