Geology Site Account

Site name: Coopers End Farm Boulders

Grid reference: TL 4649 3596

Brief description of site:

A large boulder of Hertfordshire puddingstone by the entrance to a plant hire company at Coopers End Farm, Duddenhoe End. It has since been joined by other boulders, mainly of sarsen. One of the sarsen stones has a fine collection of root holes.

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Details

The boulder of Hertfordshire puddingstone at Coopers End Farm is of large size (1.6 metres x 1.4 metres x 55 cm) and is unusual as the base of the stone is without pebbles and therefore similar to a sarsen stone.

Hertfordshire Puddingstone is a rock known as a silcrete, It was formed around 55 million years ago when the climate of Britain was hot and a layer of pebbles 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 in Hertfordshire, hence the name, and were probably carried to Essex by the River Thames when it flowed north of its present course. However, the distribution and abundance of Hertfordshire puddingstone in parts of Essex suggests that some occurrences may have a local Essex source.

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.

There are several sarsen stones here. The largest has fine root holes (see photos).

The Coopers End Farm boulders in 2020