A500 Dualling, Crewe, Cheshire: Geoarchaeological and Palaeoenvironmental Assessment

Oxford Archaeology (OA) North was commissioned to undertake a geoarchaeological and Palaeoenvironmental assessment of the proposed upgrade route of the existing stretch of A500 Crewe, Cheshire, between the A5020 (SJ 74485 52360) and M6 Junction 16 (SJ 77665 52390). The primary aim of the assessment and deposit modelling was to provide baseline data on the nature of the sub-surface sediment sequences, with particular reference to peat deposits. The sediment sequences were assessed for their geoarchaeological and Palaeoenvironmental potential, and to identify any horizons within the deposits with the potential to preserve evidence for human activity or occupation. Records from a total of 124 geotechnical interventions, including historical borehole data, were used to compile the deposit model. The geotechnical ground investigation comprised excavation of cable percussion and rotary boreholes, trial pits and dynamic (windowless) sampling, and utilised historic borehole data accessed from the BGS borehole GeoIndex database (BGS 2020). The report covers the stratigraphic sequences interpreted from the borehole lithological descriptions, from which the deposit model has been compiled. Records from a total of 124 geotechnical interventions, including historical borehole data, have been used to compile the deposit model. The modelling shows that Triassic bedrock geology was not penetrated but thick deposits of Glacial Till or Glaciofluvial deposits, probably dating to the Devensian, the last glacial episode in the Pleistocene, are recorded. The surface of these deposits defines the topography of the early Holocene landscape (c 12,000 years BP). The model shows that Holocene sediments were not found over large areas of the scheme; however, areas of peat and alluvial sediments were recorded at the western end of the site, coinciding with floodplain areas for Englesea Brook. The peat deposits have high potential for radiocarbon dating and palaeoenvironmental work. Deposits of made ground and topsoil overlie the natural sequences.