This work was inspired by research undertaken during a field survey of the later prehistoric remains of north-east Somerset (SW England) which showed that there were many cropmark sites of which little was known. The value of this evidence for the interpretation of prehistoric landscapes has been highlighted by a number of reports in recent decades. Across the country these surveys have added new dimensions to our understanding of prehistoric settlement patterns and the central role of aerial survey in elucidating these lost landscapes. The Bristol Avon Region had not previously been a primary research objective, as it lies outside the main concentration of known cropmarks. By collating the evidence from aerial photographs alongside that for previously recorded earthworks and excavations, then earlier hypotheses about this later prehistoric landscape could be re-evaluated. By taking the watershed of the Bristol Avon River as a whole it was hoped that regional differences in settlement morphology could also be identified to test these earlier hypotheses.