Speleothems - Helictite Bushes
Certainly one of the most curious formations in Wind Cave are helictite bushes. While small helictites are found in many caves, the helictite bushes are large, bush-like growths of calcite that branch and twist like gnarled trees. The largest helictite bush in the cave is about 6 feet (2 meters) tall. The helictite bushes usually grow from the floor of the cave. The helictites may form when water seeps into the cave through pores so small that the flow is controlled by capillary action and not by gravity. This allows water to move uphill and deposit calcite against the force of gravity. It is also thought the bushes may have formed underwater when the water rising from below mixed with cave waters of a different chemistry.