mercoledì 5 marzo 2008
Medieval bridges at Hemington Quarry
The quarry is located near the centre of the floodplain formed by the confluence of the rivers Trent, Soar and Derwent and is sited to exploit the thick deposits of sand and gravel which overlie deposits of Mercia Mudstone. The lower sands and gravels were probably deposited after the maximum glaciation of the last Ice Age (Devensian) between about 15,000 and 10,000 BC. The upper sands and gravels have accumulated since the start of the Flandrian period (around 10,000 BC) during which time the Trent shrank and settled into its present meander belt. During this time the lateral migration of the river has deposited between 2m and 5m of sand, gravel and alluvial silt and clay. The dynamism of the river's migration has led to the excellent survival of riverine structures in the old channels and the anaerobic conditions have ensured the survival of organic remains. The thickness of the overburden deposited by the river makes conventional archaeological prospection difficult and constant monitoring of quarrying is necessary to ensure the recording of both archaeological sites and other, natural, features.