Geology Site Account

The geologist A.E. Salter, in his landmark paper 'Sarsen, basalt and other boulders in Essex', published in the Essex Naturalist in 1914, referred to a large erratic boulder at Great Clacton but its precise location is not known. He described it as a sarsen stone 4x3x1 in size and so it should be possible to establish its whereabouts. Apart from the sarsen stone at Ramsey, this is the only other natural erratic boulder known from the Tendring district.

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.

It is remarkable that a sarsen boulder this size has travelled this far east. It would be even more remarkable if this stone originated on the North Downs of Kent and was brought to Clacton in the gravels of the River Medway. This boulder is therefore of scientific interest in the context of reconstructing the history of the evolution of the landscape of north-east Essex.

Searching for the stone would make an interesting project for a local school or society.