An Environmental History of the Upper Kennet Valley, Wiltshire, for the Last 10,000 Years
Authors: Evans J. G. , Limbrey S. , Máté I. , Mount R. , Davies S. , Fitt J. , Griffiths H. I. , Jarrett C. , Milles A. , Ringwood V. , Whittle A. 
Published: February 2014

Research on the late Pleistocene and Holocene environment and archaeology of the upper Kennet valley, north Wiltshire, is described. In concentrating the work in the valley bottom, the main aims were: (1) to see if there was a record of environment and archaeology there, and if so to detail it; and (2) to redress brasses in research towards the visible archaeology of slopes and plateaus and their environmental record.

Soils and sediments with biological and archaeological materials covered the late Pleistocene to the present and, with dating by14C and thermoluminescence, enabled a history of environment and human activity to be established.

The distinction in hydrology and environment between the valley floor and slopes/plateaus varied with time. In the upper part of the study area at Avebury, there was no stream in the earlier Holocene: woodland covered the valley floor which in some areas was similar to that of the slopes/plateaus in being dry while in other areas it was marshy. In the lower part of the study area at West Overton there was also an earlier Holocene land surface but there were locally streams and swamps, represented by the North Farm Formation. During the earlier Neolithic there was woodland clearance and some cultivation of the valley floor which initiated minor hydrological changes, namely paludification at Avebury and alluviation at West Overton. Dry grassland later developed which was little different from that of the slopes and plateaus. There was no woodland regeneration during the later Neolithic in contrast to the situation in monument ditches on the valley slopes and plateaus. Throughout the study area there was a major episode of alluviation in open country, represented by the West Overton Formation, which was probably initiated in the Beaker period and carried on until the early Iron Age. This, while not putting the valley floor out of use and indeed perhaps enhancing its fertility, provided a very different environment from that of the slopes and plateaus. Another period of alluviation, represented by theArionClay, took place in post-Medieval times.

The main Holocene deposits were not wholly allochthonous or made up solely of clastic material derived from slopewash incorporated into the river. Calcium carbonate precipitation accounted for much of the North Farm and West Overton Formations while theArionClay may derive from flocculated material redistributed from watermeadow channels in the course of their management. On the other hand, periods of arable activity in the area, often close to the river valley floor, notably in Iron Age, Roman and Medieval times, have no signal in terms of alluvium.

Archaeology, although concealed, is abundant and significantly extends the local record of slopes and plateaus. Mesolithic flints, Neolithic flints and pottery, two lines of probably later Neolithic/Beaker sarsen boulders, later Bronze Age sarsen structures, pottery and a cremation are present on the valley floor, concealed by deposits of the West Overton Formation. Medieval activity, represented on the valley sides as earthworks, extends on to the valley floor where it is concealed byArionClay and earthworks of watermeadows. The visible distribution of archaeology presents a pattern which may be of more than local significance for chalkland areas.