<span>Sinkholes are formed when the land surface above collapses or sinks into the cavities or when surface material is carried downward into the voids.</span>
Sinkholes mainly occur in what is known as ‘karst terrain’; areas of land where soluble bedrock (such as limestone or gypsum) can be dissolved by water. With cover-subsidence sinkholes, the bedrock becomes exposed and is gradually worn down over time, with the holes often becoming ponds as the water fills them in.
