This paper presents the results of the first investigation of vegetation change and human activity from a river valley west of the Somerset Levels. The record is contrasted with the pollen and archaeological record from South West uplands (Dartmoor and Exmoor) and the Somerset Levels. Vegetation change and archaeological evidence are shown to be generally consistent, with evidence from the middle valley of Mesolithic vegetation disturbance (with nearby lithics), Neolithic clearance of terraces and slopes in the lower valley and Neolithic-Bronze Age ceremonial and domestic activity, but in the upper reach the maintenance of wooded valley floor conditions probably with management until historic times. The valley floor and surrounding slope vegetation history is found to be significantly different to that of the uplands with lime and elm being significant components of the prehistoric woodland record. The data suggest that lime is restricted to terraces and lowlands below 200 metres OD throughout the prehistoric period. The pollen data from the valley suggests the lowlands had a rich and mixed ecology providing a wide range of resources and that, despite less visible archaeological remains, human activity is manifest through palynological evidence from the Mesolithic to the Bronze Age. The largest expanse of valley-floor terrace, the Nether Exe Basin, which was at least partially deforested in the early Neolithic contains a rich assemblage of Neolithic-Bronze Age ceremonial, funerary and domestic archaeology associated with an early and clear palynological record of woodland clearance, arable and pastoral activity.