Geology Site Account

Site name: Moreton Gravel Quarry (site of)

Grid reference: TL 534 074

Brief description of site:

Moreton Quarry had exposures of Kesgrave (Thames) Sands and Gravels overlain by a small thickness of boulder clay (till). Research into the nature and origin of the gravels and the till was carried out here. The pits have been landscaped and are now fishing lakes.

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Details

Moreton Gravel Quarry formerly worked the Kesgrave Sands and Gravels (Kesgrave Formation) which were laid down during the early Ice Age by the River Thames when it flowed through north Essex and Suffolk and out across what is now the southern North Sea to become a tributary of the Rhine. At Moreton about 9 metre thickness of gravel was exposed and sedimentary structures here indicate an origin in braided streams having a south-eastern flow (Millward et al. 1987). Moreton is the type locality for the Moreton Gravel and the deposits exposed here are discussed in detail by Whiteman (1992). The gravel rested on London Clay bedrock.

The gravel is mostly flint but also contains exotic pebbles of rocks from far upstream, some of which are ignimbrite (a volcanic rock) from North Wales. Hey & Brenchley (1977) examined the sands and gravels at Moreton Pit and found that of 372 pebbles in the 16 to 32 sieve fraction 73.5 per cent were flint, 12.1 per cent quartz, 10.5 per cent quartzite 3 per cent chert and 0.8 per cent volcanic origin. Their paper discusses the origin of the volcanic pebbles from this and other sites in Essex and Norfolk.

Above the Kesgrave Formation is a thickness of boulder clay, or till, which was laid down on top of these gravels about 450,000 years ago by an ice sheet during the Anglian glaciation, the most severe cold period of the whole of the Ice Age (Allen 1999). At Moreton the tilll varied in thickness from 2.5 to 9 metres (from west to east).