Geology Site Account

On private farmland one kilometre east of Cabin Hill, just south of the Essex border, is a 145 centimetre (46) long sarsen stone beneath a large oak tree. The stone is close to a patch of boulder clay (till) which was deposited by the Anglian ice sheet some 450,000 years ago. This suggests that the stone is a glacially-transported boulder, brought to this spot by the ice sheet from the chalk hills of north Essex where sarsen stones are relatively abundant. For its size, this may be the most southerly glacial erratic boulder in England. It may also be the only sarsen stone in the whole of Greater London.

The Park Farm sarsen stone. Photo: G. Lucy