Geology Site Account

Site name: Deremy's Stone

Grid reference: TM 0369 1426

Brief description of site:

A rounded boulder of the volcanic rock dolerite can be seen on the East Mersea Road. It has historical importance as a boundary marker and is probably a glacial erratic.

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Details

Opposite the Old Rectory, on the East Mersea Road, by the East Mersea road sign, is a rounded boulder of dolerite approximately 70 centimetres (two feet) square, known locally as Deremy's Stone. It was dug up on this spot in 1974 and provided with a plaque stating that it was originally placed here in 1046 to define the boundary of the manor of West Mersea granted by Edward the Confessor (Stainer 2001).

This boulder is probably a glacial erratic, carried south to Essex from Northern England by the Anglian Ice Sheet 450,000 years ago. Mersea Island is beyond the maximum southerly limit of the ice sheet but it is not difficult to imagine that rocks of some size would have been carried across this area by torrents of glacial meltwater.

Deremys Stone – a possible glacial erratic. Photo: G. Lucy