Palaeoenvironments in the Vale of Pickering. Part 2: Environmental History at Seamer Carr

A three-dimensional study of the vegetational history of Seamer Carr from the Devensian Late-glacial to the Atlantic period has been made with the aid of six sites in the main basin. Five of these are close to the margins of the organic deposits and the sixth is from deep basin deposits. The Godwin zonation scheme has been used to allow a direct comparison with the survey of Walker and Godwin (1954). A composite section through the basin deposits, based on the detailed contour plan described in Part 1, shows that, pre-Zone IV, the open water margin abutted the dry land, and that during Zone IV reedswamp and carr gradually filled in the edges of the lake. Large expanses of fen carr occupied Seamer Carr during Zone V, but a rise in water level during Zone VI was responsible for the area reverting to reedswamp. At the Boreal/Atlantic transition, coincident with the rise in the alder pollen curve, there is a thick band of highly humified, acid peat, full of microscopic pieces of charcoal. Analysis through this band at one of the specially selected sites on East Island produced evidence of local disturbance, seemingly anthropogenic, at the wetland margin. There were two other special sites in West Embayment that were sampled for pollen analysis. The first was located over a radiocarbon dated Zone II organic deposit, sealed beneath a Zone III calcareous sand layer. The second was located in a late Mesolithic organic mud radiocarbon dated to c. 8000 BP and containing an assemblage of microliths of late Mesolithic type, identified tentatively as a composite tool (A. David pers. comm.).