The Somerset Levels are the largest area of low-lying ground in south-west England, covering an extensive region between the highlands of Exmoor, the Brendon Hills and the Quantock Hills to the west, and the Cotswold and Mendip Hills to the east (Pl. XXIII, inset). The Quantock Hills and the Mendip Hills directly border the Levels themselves, and reach heights of over 250 metres above sea level. The valley between extends to 27 metres below sea level, but is filled to approximately the height of the present sea by a blue-grey clay. The Levels are bisected by the limestone hills of the Poldens, and both parts have other smaller areas of limestone and sand projecting above the peat deposits that cap the blue-grey clay filling. In this paper we are concerned with the northern part of the Levels, an area at present drained by the River Brue.

The flat, peat-covered floor of the Brue Valley is some six kilometres wide and is flanked on the north by the Wedmore Ridge, and on the south by the Polden Hills (Pl. XXIII). In the centre of the valley, surrounded by the peat, is a group of islands of higher ground, Meare, Westhay, and Burtle. These islands, which would always have provided relatively dry ground in the Levels, are linked together by Neolithic trackways of the third millennium B.C. Several of these trackways formed the basis of a paper in these Proceedings in 1968 (Coles and Hibbert, 1968), which continued the work of Godwin and others (Godwin, 1960; Dewar and Godwin, 1963).