Geology Site Account
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Little Oakley Channel Deposit SSSI, LITTLE OAKLEY, Tendring District, TM223294, Site of Special Scientific Interest
Site category: Thames (pre-diversion)
Site of Special Scientific Interest designated for the importance of its geology. The site consists of an interglacial channel, part of the Kesgrave Sands and Gravels, which was laid down by a former course of the River Thames, at the point where it may have been joined by the early River Medway. It has yielded numerous fossils. There are no current exposures.
Many important fossil discoveries depend on the right person being in the right place at the right time and the Little Oakley channel is a classic example of this.
During the Summer of 1939, only a few months before the outbreak of the Second World War, a sewer trench was being dug along the road through Little Oakley and the excavation was noticed by amateur geologist Samuel Hazzledine Warren as he was driving through the village. The sand thrown out of the excavation was found to be rich in shells, deer antlers and mammal bones and Warren described the discovery in the pages of the ‘Essex Naturalist’ in 1940. Because of the war no further investigation was carried out at the time but it is surprising that, despite the apparent importance of the discovery, the site did not receive any more attention until the 1980s. Using Warren’s notes, geologists then relocated the site using mechanical excavators. Warren had correctly identified the deposit as the infilling of a river channel of the same age as the famous Cromer Forest-bed in Norfolk which dates from an early part of the Ice Age before the arrival of the Anglian ice sheet.
The channel is cut into the Oakley Gravel, part of the Kesgrave Sands and Gravels, which was laid down by a former course of the River Thames, at the point where it may have been joined by the early River Medway. The Oakley Gravel is the downstream equivalent of the Ardleigh Gravel and about 550,000 years old. The channel contains fossils that include the bones rhinoceros, giant deer, hyaena, horse, boar, vole and fish, a rich assemblage of freshwater shells and a fine pollen record which has enabled geologists to reconstruct the flora and fauna of this distant period of the Ice Age. The channel can be dated by comparing the assemblage of mollusc shells with those from sites in north Norfolk, and the pollen assemblage with sites in the Netherlands. These indicate a broadly ‘Cromerian’ age, though it is not clear whether it is the same age as the interglacial deposits at Ardleigh Gravel Pit (see separate site entry) or later. This is confirmed by analysis of amino acids from mollusc shells. Although the channel’s exact age is still not known it is thought to be about 575,000 years old. A remnant of the much older Red Crag, for which Little Oakley is also well known (see separate site record), lies adjacent to and just below the channel deposit.
The 1980s excavation was backfilled and there is now no indication on the surface that this strip on the edge of a farm field is one of the most important geological sites in Essex.
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Reference: Bridgland 1994 (p. 305-313)
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