sinkhole is a hole formed in soluble rock by action of water.
It is a sink hole if it reaches the surface.
sinkhole
Sinkhole and a cavern
A sinkhole is formed when the roof of a cave collapses.
A large hole formed when a roof of a cave collapses.
A cave or sinkhole.
A large hole formed when a roof of a cave collapses.
A sinkhole forms.
A Shakehole or Sinkhole.
how deep is it
When rock above a cave collapses, it forms a sinkhole. Sinkholes are depressions in the ground that are often caused by the erosion of underground caves or channels.