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Geology of Crystal Cave
The rocks that make up the area are sedimentary rocks which are also known as the Prairie Du Chein formation. The Prairie Du Chein formation is about 485 million years old and has a sandy texture/feel. There are many other locations in western Wisconsin where the Prairie Du Chein formation is present. The layer is visible in the bluffs along the Mississippi River. There are also small amounts of flint and “bog iron” prevalent in the sandstone and dolomite.
The darker layer in the photography above is a small peice of flint located in the dolomite layer in the Prairie Du Chein formation.
There are three distinct layers that are evident in the cave, each having a different texture. The layers are named New Richmond, Shakopee, and Oneoda. The Shakopee layer is the youngest, mainly consisting of limestone and dolostone formed in a relatively deep water environment. The second layer down is the New Richmond, which consists of sandstone that was formed in a relatively shallow water beach environment. The largest room in the cave, the ball room, is located in the New Richmond layer. The oldest layer is the Oneada. This layer consists of thick dolomite layers.
There is no running water in the cave at the current date. The water table is approximetly 30 feet below the floor of the Ball Room.
The photograph above is of the group in the largest room of the cave called the Ball Room. The Ball Room is located in the New Richmond layer.