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Cave Formation

In order for a cave to be considered a cave, it must meet some simple criteria. A cave must be big enough to fit people in it, it has to be formed naturally, and it has to be deep enough to be in total darkness.

The main factor in cave formation is carbonic acid reacting with limestone. Carbonic acid is created when water falls through the air or percolates through the soil and collects carbon dioxide. This carbonic acid then infiltrates down into cracks in the limestone and start to dissolve the rock around those cracks. As more and more dissolving occurs, the cracks eventually become caverns big enough to fit people in to. As the cavern gets bigger and bigger underground, its ceiling gets eroded and the ground above collapses into the cavern. This formation is known as a sinkhole and there is a great example of one behind the gift shop at Crystal Cave. Even further down the road, caverns that are in line with each other can collapse, forming a valley known as an uvala.

These caves can be dangerous as the formation dissolves more and more rock near the surface, causing the earth’s surface to collapse, creating sink holes. These are known as karst processes.

A large 5 meter deep sink hole that collapsed in 1982. This is located just outside the visitor center, and once was a room in the cave system.

Cave Formations

Cave formations or speleothem at Crystal cave are similar to that of many caves. They include stalactites, stalagmites, columns, and soda straws. These formations are created by calcite deposits in the water that intrudes into the cave. Calcite is picked up in the cave rock and runs through the limestone. Once it leaks out it creates the aforementioned formations. Soda straws are an especially unique feature because they are hollow inside. When the water falls from the ceiling of the cave, calcite in the water remains present on the ceiling. This starts the formation of a soda straw. They grow anywhere from centimeters to near a half meter. Gradually as this formation of calcite progresses, it becomes a fragile formation that is easily broken.

Small stalactites forming on the ceiling of the cave. These formations are only a couple inches long.


The stalactites and stalagmites have formed into a single pillar.


Dripwater from the cave walls has precipitated calcium carbonate to form this flowstone.

Website created by Mike Molnar, Jim Pintaro, Greg Smoczyk, and Nick Lorenz

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