Geology Site Account

Site name: The Leper Stone

Grid reference: TL 5199 3496

Brief description of site:

Large sarsen stone on the roadside verge north of the village of Newport.

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Summary of the geological interest

On the grass verge on the Cambridge Road (B1383) at the northern entrance to Newport village is a large boulder known locally as the Leper Stone. This boulder is a sarsen stone, a block of extremely hard sandstone that was formed about 55 million years ago during the Palaeocene period in sandy strata called the Reading Beds that occur on top of the Chalk. The stone is called a glacial erratic as it was carried to Essex by the Anglian Ice Sheet which covered almost the whole of Britain during the coldest period of the Ice Age, some 450,000 years ago. It probably originated on the Chalk downland of Cambridgeshire.

It is clear that the stone has been moved here by humans and may have been ploughed up from a local field. It may have been placed here as a boundary marker but when this was done is not known.

Scientific interest and site importance

Sarsens are not uncommon in Essex, but this is a very large example. Sarsens formed when the climate of Britain was hot, and a layer of sand beneath the surface of ground became cemented with quartz. They are thus very resistant to erosion and have survived the rigours of the Ice Age. The climate conditions under which sarsens were formed has been compared to the present day climate in the Kalahari Desert and parts of Australia.

The Leper Stone is of educational importance as it is the Countys largest standing stone, as well as being one of the most conspicuous and best-known erratic boulders in Essex. It is also of historic interest, linking geology, archeology and social history.

Other information

Near the stone is said to have been the site of St Leonards Hospital, founded in 1156, which is thought to have been a hospital for lepers, hence the name Leper Stone. Part of the hospital wall still remains near the stone, which consists of red bricks and blocks of hard chalk, called clunch.

The Leper Stone. Photo: G. Lucy