Vale of Pewsey

The Vale of Pewsey is an area in the Kennet district of Wiltshire, England to the west of Devizes, centred on the town of Pewsey.

Geography

The vale is an extent of lower lying ground separating the chalk downs of Salisbury Plain to the south from the Marlborough Downs to the north. It is around convert|30|km|mi long and around convert|5|km|mi wide. At the western end is the town of Devizes. Larger settlements in the vale include Pewsey and Burbage with many smaller villages, the larger ones including Bishops Cannings, Etchilhampton, Urchfont, Chirton, Alton Priors, Woodborough, Milton Lilbourne, Easton Royal and Wootton Rivers.

Although not itself part of the downs, the vale is included as part of the North Wessex Downs AONB (Area of Outstanding Natural Beauty).

The vale is a major east-west feature opening to the west towards the Bristol Channel, but is drained by the headwaters of the Salisbury Avon, rather than the westward-flowing Bristol Avon. The river cuts through the chalk scarp to the south at Upavon and crosses Salisbury Plain towards the south coast. The higher part of the eastern vale south of Burbage is drained by the River Bourne, which cuts the scarp at Collingbourne Kingston, joining the Avon at Salisbury. Since the area is not believed to have been glaciated, this probably indicates that the course of the rivers pre-dates the modern topography.

The vale is not used by any major roads, but is followed by a railway and canal as a route between the London Basin and the west. To the north of Burbage the head of the Avon valley, draining west into the vale, meets the head of the River Dun, draining east to the Kennet and the Thames. The valley floor at around convert|150|m|ft above sea level provides a route through the downs which locally reach 200 to 300 metres. The Kennet and Avon Canal and the main line railway from London to the south-west make use of this route, the canal using the Bruce Tunnel. Formerly another rail route between Andover and Marlborough also followed this gap. Another line branched off towards Bath via Devizes at the western end of the vale.

Geology

The vale lies along the eroded core of an anticline, a westward extension of the Mendip Axis, with a relatively thin covering of Mesozoic sediments folded upwards over an up-faulted horst of Palaeozoic rocks.Melville, R.V. & Freshney E.C. (4th Ed 1982), "The Hampshire Basin and adjoining areas", British Regional Geology series, Institute of Geological Sciences, London: HMSO, ISBN 0-11-884203-X p115] The floor of the vale is floored by Albian (Lower Cretaceous) beds of the Upper Greensand, exposed by removal of the overlying chalk. It is surrounded to the north and south by chalk scarps which close to the east near Burbage. There is also a small inlier of Greensand to the east at Shalbourne; ["Chilterns: Sheet 51N 02W Solid Geology", 1:250,000 Geological map series, British Geological Survey, Keyworth, 1991] this area drains northwards to the Kennet.

References