What are sinkholes and what causes them?

"Once those caves start to collapse, the materials above will simply funnel in," says Dr Anthony Cooper, a principal geologist at the British Geological Survey, which maps the country for rock types susceptible to sinkholes and carries out surveys for developers, builders and individuals worried about the prospects of the land caving in beneath them. read more

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. read more

A dramatic 10 metre sinkhole that appeared in St Albans. They are usually caused by erosion underground. And even though sinkholes appear to form suddenly, usually the underlying causes of them have been brewing for some time. However, there are human processes that can also cause the formation of sink holes. read more