Geology Site Account

Site name: Lucas Farm boulders

Grid reference: TL 5766 1375

Brief description of site:

Outside Lucas Farm are two sarsen stones (the largest 90 x 90 x 40 centimetres in size) and two lichen-covered limestone boulders (the largest 110 x 70 x 70 centimetres in size).

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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.

Like the sarsen stones these limestone boulders have been here a very long time and are almost certainly erratic boulders left behind by the ice sheet. They may have originated in Derbyshire or Yorkshire.