Geology Site Account

Site name: Fingringhoe Wick Nature Reserve, Fingringhoe.

Grid reference: TM 045 195

Brief description of site:

Fingringhoe Wick Nature Reserve is a former gravel pit with good exposures of glacial gravel.

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Summary of the geological interest:

Fingringhoe Wick was a working gravel quarry, known as Freshwater Pit, between 1924 and 1959. Visible in many places are mounds and banks of glacial sand and gravel (known as Upper St. Osyth Gravel) which was deposited some 450,000 years ago by colossal torrents of meltwater issuing from the Anglian ice sheet, the edge of which was then situated only 12 kilometres west of here. At that time ice covered almost all of Britain to a maximum thickness of over one kilometre.

The gravel therefore provides evidence of an exceptionally cold period of the Ice Age, a time when Essex was barren of virtually all life - in stark contrast to the abundant flora and fauna that can be seen at Fingringhoe Wick today. A permanent cliff of gravel exists in the centre of the reserve where pebbles of several different rock types can be collected. These rocks provide clues to the origin of the ice and the rocks over which the ice sheet passed.

There are fine views of the Colne estuary from the edge of the reserve.

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Scientific interest and site importance

Fingringhoe Wick has been cited as providing exposures of Lower St. Osyth Gravel and Upper St. Osyth Gravel (Bridgland 1994). The Lower St. Osyth Gravel was laid down by the River Thames when it flowed through central Essex, to the south of Colchester, and out across the low-lying land that is now the North Sea to become a tributary of the Rhine. Shortly afterwards the Anglian Ice Sheet blocked the valley of the Thames upstream and diverted the river to its present course. As the ice sheet spread into central Essex the former Thames valley became a channel for glacial meltwater which flowed across the Fingringhoe area laying down the Upper St. Osyth Gravel, a typical glacial outwash deposit. The junction between the two gravels therefore represents the point at which the Thames ceased to flow through central Essex. The Thames at that time was a very large, braided river and its diversion must have been a catastrophic event.

Fingringhoe Wick is important because there are very few other sites in Essex where glacial gravel (in this case the Upper St. Osyth Gravel) can be so readily examined. The Lower St. Osyth Gravel is not now visible here although it is occasionally revealed in the active quarry to the north of the site.

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Other information

Fingringhoe Wick was purchased by the Essex Wildlife Trust in 1961. For its biodiversity importance the site is included within the Colne Estuary Site of Special Scientific Interest (SSSI). There is ample car parking but no access to the site by public transport.

Visitors examining the cliff of glacial gravel at Fingringhoe Wick Nature Reserve. Photo: W.H. George