Geology Site Account

Site name: Ashdon Sarsen Stone

Grid reference: TL 5868 4212

Brief description of site:

Buried in the ground on the side of the road near the road junction (by the Rose and Crown public house) is a sarsen stone at least 80 centimetres long. The stone is between the road and the steps leading down to the stream and is almost completely buried beneath the turf. It was clearly placed at this spot in the distant past and the fact that the soil has now risen to be level with the top surface is indication that it has been here for centuries, perhaps as long as the junction has existed.

Cutting away the turf to fully expose this stone would be an interesting and worthwhile project.

Details

Sarsens are extremely hard boulders of sandstone formed around 55 million years ago when the climate of Britain was hot and a layer of sand beneath the surface of the ground became cemented with quartz. They are thus very resistant to erosion and have survived the rigours of the Ice Age. They originated on the chalk downland north and west of Essex and were carried here by rivers and glaciers. After retreat of the ice they became concentrated in river valleys.

The formation of silcretes (which includes sarsens and puddingstones) has been the subject of recent scientific debate. Research has compared the conditions under which sarsens and puddingstones may have been formed with the present day climate in the Kalahari Desert and parts of Australia.

The Ashdon sarsen stone, almost buried beneath the turf. Photo: G.Lucy