Geology Site Account

Site name: Lords Bushes

Grid reference: TQ 413935

Description of site:

Lords Bushes and Knighton Wood are areas of adjoining oak and hornbeam woodland on the border of Essex and Greater London. The woods form part of the eastern edge of the Epping Forest ridge. Lords Bushes is in Essex (Epping Forest District) and Knighton Wood is in the London Borough of Redbridge.

The woodland has exposures of sand and gravel dating from the early part of the Ice Age. The geology revealed by any significant excavations in the wood should be recorded. The site has the potential for promotion of geology.

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Summary of the geological interest:

The woods sit on an extensive patch of what is known as Woodford Gravel, the origin of which is not entirely clear. The proportion of angular and rounded flint, and of other rock types, indicate that it was deposited by a northward-flowing river, probably a south-bank tributary of the ancestral Thames. When this river was in existence is difficult to determine but it is thought to have been over one million years ago. The height of this patch of gravel above present sea level is about 80 metres (260 feet) which shows how much erosion of the surrounding land has occurred since that time.

Although there are currently no permanent exposures, the sandy gravel is visible on the banks of ponds which are disused gravel pits, and also in the roots of fallen trees.

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Scientific interest and site importance

The high level patches of gravel in the vicinity of Epping Forest are thought to have been laid down by south-bank tributaries of the ancestral Thames. This theory is supported by the fact that the gravel outcrops decline in elevation northwards. It therefore appears that this particular gravel, named Woodford Gravel (Ellison 2004), was deposited by a river flowing from what is now the Weald of Surrey northwards across East London to join the Thames which at that time flowed across north Essex and Suffolk.

The pebble assemblage contains Lower Greensand chert from The Weald and is comparable to that typical of streams draining the Weald, south of the present Thames. On the basis that the deposits are of Weald origin it has been suggested that the stream responsible was the Wandle (Gibbard 1994).

Woodford Gravel covers most of Lords Bushes but London Clay bedrock outcrops at the surface along the eastern edge. Disused gravel pits exist on the western side of the wood which are now ponds (Hanson 1983). The pits are recorded as being worked in the 1880s. Small streams rise from the junction between the gravels and the clay.

There are minor exposures of gravel in the wood, in pond banks etc. This site is important because there are very few places where Woodford Gravel can be seen.

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Other information

Lords Bushes and Knighton Wood are part of Epping Forest and are accessible at all times. They are also a site of special scientific interest (included within Epping Forest SSSI). The site is within easy walking distance of Buckhurst Hill or Roding Valley Underground stations.

A bank of gravel on the side of the lake in Knighton Wood. The gravel was probably deposited over 700,000 years ago by a northward-flowing tributary of the ancient pre-diversion Thames. Photo: G. Lucy