Collapse or solution sinkholes form as underlying limestone bedrock dissolves and can no longer support the overlying soil, either sand or clay. A hole may form in the land surface and possibly fill with water. Sink holes or shakehole occurs in areas of land where soluble bedrock can be dissolved by water. With the cover-subsidence sinkholes the bedrocks becomes exposed and gradually worn down over time. As a result these holes often becomes ponds as the water fills them.