Moatfields Park (HEMTF05)

Clients: Hertsmere Borough Council

Author: Jane Corcoran

Site supervisor: Craig Halsey

An auger survey of the fills of a medieval moat, together with a topographic survey of the moat’s profile, was undertaken by MoLAS geoarchaeologists at Moatfields Park, Bushey between the 20th October and the 2nd November 2005. The aim was to inform the strategy for a subsequent watching brief on clearing and de-silting works. The Bushey Moatfield, once the site of Bournhall Manor, is the largest moated site in Hertfordshire. Since little is known about it the Friends of the Moatfield have been awarded funding from the Local Heritage Initiative to carry out archaeological research into the site and to raise awareness in the local community.

The site is one of many medieval moated sites once found over the expanse of London Clay that extends across the northern part of Greater London and adjacent counties. The impermeable clay subsoil, together with the location of the site on the valley floor of a tributary of the Colne, is likely to have helped water retention in the moat, which was probably at least seasonally water-filled. The clay soils would have been heavy to work and frequently waterlogged and, as a result, areas of the London Clay appear to have been relatively little exploited by prehistoric and early historic farmers. Dense woodland is thought to have existed in these areas until the medieval period, when population pressure led to woodland clearance and expansion of settlements and agriculture onto the claylands. Documentary evidence suggests that the moated site of Bournhall was constructed at this time, in the early years of the thirteenth century.

Two transects of augerholes were drilled across the south-eastern side of the moat and demonstrated that up to 3m of moat fills exist below the present ground level. A possible recut was identified that widened the moat without substantially deepening it. The fills of the earlier cut are indicative of still standing water and probably represent a gradual accumulation of naturally derived sediments. Indirect evidence of forest clearance, medieval land-use and activity within the moated enclosure are likely to be available from environmental remains such as pollen, seeds and insects preserved in the moat fills.

Although the de-silting program will only impinge upon the uppermost parts of the moat fill ? consisting of oxidised clays and topsoil horizons thought to be fairly modern in date ? the geoarchaeological auger survey has established that the fills of the earlier, narrower and deeper moat could form the focus of future research on the site.

This site report is extracted from MoLAS 2005: annual review