Geology Site Account

Site name: The Coppice

Grid reference: TQ 573993

Brief description of site:

Area of woodland with a varied geology and the potential to create exposures in Warley Gravel and/or Bagshot Sand.

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Summary of geological interest

The Coppice is a semi-natural broad-leaved wood north of the village, through which flows a tributary stream of the River Roding. The wood is designated as a biological Site of Special Scientific Interest (SSSI).

The bedrock geology of the area consists of London Clay, overlain by Claygate Beds and Bagshot Sand. On top of the Bagshot Sand is an extensive spread of Warley Gravel (called Stanmore Gravel on modern geological maps), which dates from an early period of the Ice Age and may be over a million years old. The origin of the Warley gravel is unknown, but one theory is that it was deposited by a south bank tributary of the early Thames when the Thames flowed across central Essex.

The modern stream has cut a deep valley through the Warley Gravel and underlying Bagshot Sand and exposed the Claygate Beds in the valley bottom. A public footpath leads north from School Lane along the western edge of the wood and the ground falls away steeply on the right down to the stream. On the left hand side of the path at one point is a small bank of yellow-brown Bagshot Sand. Further along the path the level ground of an old overgrown gravel pit can be seen on the left and here, in places, there are rounded pebbles and cobbles of flint. There are also various rock types that have clearly been transported considerable distances before being incorporated in the gravel. The path is paved for most of its length with well-rounded pebbles from this gravel.

The low bank of Bagshot Sand could be cleaned to provide a very fine, albeit small, exposure. The steep bank of the old gravel pit, adjacent to the field, could also be excavated to create an exposure of Warley Gravel. This work would be of great value as exposures of Bagshot Sand and Warley Gravel are very rare in Essex.