Geology Site Account

Site name: Newport Puddingstone

Grid reference: TL 5214 3358

Brief description of site:

A large boulder of Hertfordshire Puddingstone on the grass verge outside Newport Village Hall in Station Road.

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Details

On the grass verge outside Newport Village Hall is a large and colourful boulder of Hertfordshire puddingstone about 1.8 x 1.15 x 0.75 metres in size.

Hertfordshire puddingstone is a unique type of rock containing well-rounded flint pebbles bound together with quartz cement. It is named after its resemblance to a plum pudding and the fact that it can be found in Hertfordshire in-situ. The cement and pebbles are homogeneous and both equally hard, which makes puddingstone a very tough rock.

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. It was thought that 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 North-west Essex suggests that these occurrences may have a local 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.

Isolated erratic boulders are also of historic interest as there is usually speculation about if, when and why stones were moved to their present position. This particular stone was moved to outside the Village Hall from the outskirts of the town in the 1950s when the Village Hall was built. It came from a spot just beyond what is now the M11 bridge. Some years ago it was moved to the Common but was moved back to the Village Hall as a result of demands by local residents. In 2008 it was moved a few metres to its present position on the grass verge.

The puddingstone outside the village hall. Photo: M. Ralph.