On Monday, February 3, 2014 11:13:19 AM UTC, Joe Egginton wrote:
On 03/02/2014 09:07, Malcolm wrote:



In article ,

Weatherlawyer writes

On Sunday, 2 February 2014 23:22:17 UTC, Joe Egginton wrote:

A 30ft sinkhole has swallowed a car in High Wycombe, from the photos



there's no water at the bottom so it can't be an underground stream. I



don't think there's any mines around there. So what caused the sink

hole?







http://www.bbc.co.uk/news/uk-england...herts-26010192



Fairly common in any severe volcanic spell.

Usually in such spells there is also a plethora of flood stories.

The rest, as they say, is natural history.



They may or may not occur where there are volcanoes, but that is surely

irrelevant in 21st century High Wycombe! The two commonest causes are

old mine workings and the dissolving of limestone or sometimes sandstone

by the action of water.





I'm no geologist, thinking about it rationally.

The weight of the clay probably has something do with it. Limestone

being porous there must be more air in it, than clay which can soak up

water like a sponge. The limestone may have been compressed. Also, the

heavy clay on top of the limestone, will raise the water pressure going

through the limestone.

Or it's an old chalk mine, as Mike's link said. shakes head