Campbell, S., Scourse, J.D., Hunt, C.O., Keen, D.H. & Stephens, N. 1998. Quaternary of South-West England. Geological Conservation Review Series No. 14, JNCC, Peterborough, ISBN 0 412 78930 2.
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This section describes a series of sites chosen to conserve representative examples of the terrace gravels of the River Avon and of later landscape development in Avon. The Avon terrace gravels were classified as the Avon Formation by Campbell et al. (in prep.), and, as has been recognized since the work of Davies and Fry (1929) and Palmer (1931), it can be divided on morphostratigraphic grounds into three distinct aggradations. The Bathampton Member lies approximately 3 m above the modern floodplain, with the Stidham and Ham Green members lying about 15 m and 30 m, respectively, above it. All of these units comprise predominantly trough cross-bedded gravels, and all contain substantial quantities of erratics. Many terrace gravel sites have been known since the last century (Weston, 1850; Dawkins, 1865; Moore, 1870) but few survive to the present day and still fewer have been the subject of modern investigations. Many sites recorded in the literature as 'richly fossiliferous' have been lost under encroaching urban development, for instance the cluster of sites at Twerton.
The stratigraphy and age relationships of the Avon gravels are particularly important because in the valley of the Avon are preserved remains of an extensive pre-Anglian glaciation. The age of this glaciation and its limits have long been subjects for scientific controversy (Kellaway, 1971; Kellaway et al., 1975; Kidson and Bowen, 1976; Gilbertson and Hawkins, 1978a; Andrews et al., 1984; Jones and Keen, 1993), and establishing the chronology of the Avon gravels offers one possible route to determining a timescale for this event.