Geomorphology

Fall 2005

Cave Formation:

Crystal Cave is the longest cave in all of Wisconsin. In order to understand the formation of Crystal Cave, it is first important to understand what defines a cave. There are three rules that must be satisfied in order for a formation to be considered a cave. First of all it needs to be large enough for a person to fit into, secondly it needs to be naturally formed, which eliminates anything man-made, and lastly it is necessary that parts of the cave are filled with total darkness. Crystal Cave fills all of these requirements, and thus can be considered a cave.

Crystal Cave specifically gets its name from the quartz crystals that can be seen in many of the rock formations in the cave. They can be seen in several rooms in the cave and glitter in the light. In general there are three different rock layers that can be seen inside the cave. The top layer is the Shakopee layer, the middle sedimentary layer is the New Richmond, and the bottom layer of rock is known as the Oneida.

The cave itself took several thousand years to form, and nobody is quite sure exactly when it took place. The main force that drove the cave to form the way that it did was carbonic acid flowing through the cave system. Today, however, there is no natural water flowage in the cave.

When rainwater falls it dissolves some carbon dioxide and becomes slightly acidic. Also when it penetrates the soil it picks up more acids and eventually reaches the surface of the bedrock, where it penetrates cracks in the rock and slowly eats away the surface, making the cracks larger and deeper. Over long periods of time this forces the surrounding rock walls to collapse, leaving hollow areas, which are the base of the caves.

By: Brandon Miller

Diagram of cave formation