What is a sinkhole?

  • 3 February 2014
Image copyright PA

What is a sinkhole?

A sinkhole is a hole in the ground formed when the rock underneath dissolves by groundwater.

Where do they form?

Sinkholes usually form in areas of chalk or limestone - types of rock slowly that dissolve with rain water.

Sinkhole collapses are pretty common in the American state of Florida. Virtually the whole of the state is a limestone platform.

But sinkholes are extremely rare in the UK.

What are they like?

Sinkholes can be of all different sizes ranging from just a few metres to large ones around 20 metres deep.

Collapsed sinkholes generally have steep rock sides and may have streams that then flow underground.