Geology Site Account

Site name: Pound Wood Nature Reserve

Grid reference: TQ 819886

Brief description of site:

The high ground of Pound Wood is capped with ancient gravel, known as Daws Heath Gravel, which was deposited by a northward-flowing Medway river over 700,000 years ago. It is one of the highest and oldest terraces of the River Medway. The pebbles in the gravel are mainly flint but there is also a proportion of distinctive rocks from the Weald of Kent that proves its Medway origin. It is a publicly accessible site with potential for promoting geology. There are several disused gravel pits in the reserve.

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Summary of geological interest:

Essex Wildlife Trust's Pound Wood Nature Reserve is situated on the northern slope of the ridge of high ground at Daws Heath. Here the ground rises to over 70 metres (220 feet) above sea level and the varied geology of the wood has resulted in a great variation of woodland types.

The geology of the area consists of the familiar London Clay, overlain by the sandy clay of the Claygate Beds which is present at the lowest part (north end) of Pound Wood. As the ground rises to the south the Claygate Beds become increasingly sandy until they pass into fine yellow Bagshot Sand. The Bagshot Sand is overlain by 'Daws Heath Gravel' which caps the summit of the ridge. The gravel is therefore present at surface at the highest part (south end) of the wood and the rounded pebbles can be seen on the paths and in the roots of fallen trees.

Daws Heath Gravel is an ancient remnant of a formerly much more extensive deposit of river gravel that was left behind by the River Medway when it flowed across eastern Essex in the early part of the Ice Age (see Rayleigh hills). It is one of the oldest of the high level east Essex gravels and its Medway origin is demonstrated by the presence of numerous pebbles that originate in the Weald of Kent.

In the early twentieth century there were several gravel pits on the Daws Heath ridge and one of these, known as Bramble Hill Pit, is clearly shown on the 1923 Ordnance Survey map just west of Bramble Hall. This pit was visited by the Geologists' Association in 1906 and the report of the visit states that a 'fair sized' boulder of Lower Greensand chert from the Weald was found in this gravel but the age of the gravel and the connection with the Medway was not then appreciated. Other rock types from Kent are also present, including sarsens. A large sarsen (nearly half a cubic metre in volume) was reported to be visible on the surface near where the Little Haven Hospice now stands (Lake et al. 1986 p. 26).

Pound Wood Nature Reserve is open to the public during daylight hours. There is no car park for the reserve but on street parking available nearby.