Monument record 0952800000 - Upper Palaeolithic and Mesolithic at Denham Area 4

A survey of 107 boreholes was done across the site before test-pitting and trial trenching in order to model the palaeolithic and Mesolithic terrain and deposits. The topography of the subsurface gravel provides a good indication of the presence of Holocene sediments, gravel islands and the location of former palaeochannels. Two slightly raised buried gravel islands were identified within the Rusholt Brook and the Colne. The Colne island is to the west of the modern river and next to a former deep channel of the Colne adjacent to its current course. The island is fringed with black clays and localised alluvium that may be archaeologically and environmentally significant. The Rusholt Brook island is in the north part of the Rusholt Brook's floodplain and is sealed by alluvium. The floodplain of the Alder Bourne is of medium potential for Palaeolithic or Mesolithic deposits. The alluvium here was sandy and thin. Three palaeochannels of the three watercourses on site were found. Deep peat was found along the western edge of the present Colne and in the north-east of the site where former channels might have existed. Thinner peat existed between the Colne and the Rusholt Brook and a little over the Colne island. The buried islands are likely to be a focus of human activity and the palaeochannels have high palaeoenvironmental potential (B2).
Test-pitting and trenching identified the location of several sites of high archaeological significance and potential. Three in situ flint scatters were identified and recorded at the edges of the two gravel islands. These include a long blade industry dating to the Late Glacial and sealed by a peat deposit dated to 9300+/-50 BP; an Early Mesolithic scatter, radiocarbon dated to 9131+/- BP and; a small undated scatter, also likely to be of Mesolithic date. The Late Glacial/Early Post-Glacial flint scatters have direct parallels with other well-known sites in the immediate area, especially with the site at Three Ways Wharf and the Mesolithic site at Sandstone. Deep peat deposits alongside the River Colne and shallow peats along the Rusholt Brook were recorded and radiocarbon dated to the Mesolithic period. The sequences contain better preserved pollen and have a greater temporal range than those from Three Ways Wharf (B1).
A total of 135 test pits excavated to investigate three possible in-situ flint scatter sites, recovering flints from the Late Glacial to Mesolithic periods. The watchign brief did not record any archaeological finds or features. See report for more detail (B3).
Desk-based assessment concluded that development on the site would have significant impact on archaeological remains (B4).