Geology Site Account

Site name: Lexden Brick Pit (site of)

Grid reference: TL 975 254

Brief description of site:

A former brick pit at Lexden, whose exact site is uncertain, yielded a large number of Ice age fossils in the middle of the nineteenth century, including the bones of mammoth and rhinoceros and beautifully preserved beetles. The fossils are thought to be from an interglacial period about 200,000 years ago.

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Details

On the south side of the Avenue of Remembrance, about 400 metres east of the Spring Lane roundabout, is a wooded area that was originally a gravel pit in the terrace gravel of the River Colne. Near here is the site of the famous Lexden Brickworks whose pit yielded a large fossil fauna and flora in the middle of the nineteenth century. The main interest of the pit was a 10 metre wide trough in the gravel which contained a layer of clay overlain by peat, at the junction of which was found bones of a mammoth and a narrow-nosed rhinoceros. The amateur geologist John Brown of Stanway obtained many fossils from this pit including a fine set of rhinoceros jaws that was donated to Londons Natural History Museum.

Old records state that the most notable thing about this deposit was the large number of fragments of beetles in a remarkable state of preservation with the striking metallic colours of the elytra, or wing cases, still preserved. At least eleven species of beetle were found and because many beetle species have a particular preference for warmth or cold geologists have been able to make assumptions about the climate at the time the peat was formed.

The peat and the clay are thought to have been deposited about 200,000 years ago (oxygen isotope stage 7) during an interglacial stage of the Ice Age. The climate, despite the presence of mammoth, was not unlike that of Essex today although fossil pollen in the peat indicates that the area that is now Lexden was extensive open grassland with few trees. In the 1880s the pit was ploughed over and its exact location is now not known.

Crown view of a mammoth tooth from Lexden. The tooth is 19 centimetres (7½ inches) long and is now in the Natural History Museum, London. Illustration: © The Palaeontographical Society