Karst landforms are generally the result of mildly acidic water acting on weakly soluble bedrock such as limestone. The mildly acidic water begins to dissolve the surface along fractures in the limestone bedrock. Over time, these fractures enlarge as the bedrock continues to dissolve. Openings in the rock increase in size, and an underground drainage system begins to develop, allowing more water to pass through the area, and accelerating the formation of underground karst features.