Geology Site Account

Site name: Chelmsford Museum Puddingstone

Grid reference: TL 7023 0556

Brief description of site:

A fine boulder of Hertfordshire puddingstone (70cm x 60cm x 30cm in size) formerly stood by the entrance door of the museum. It now sits in the Museum grounds and has been provided with a signboard.

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Details

Hertfordshire Puddingstone 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.

Chelmsford Museum Puddingstone in its new position in 2021. Photo: Ian Mercer