Cholesbury Camp is a hillfort in the central Chilterns, a scheduled ancient monument that has been dated to the Iron Age. The field we worked in lies just outside the hillfort, was not part of the scheduled area, and had not been previously surveyed. But over many years rectilinear marks in the grass during dew, snow and frost had led the owners to wonder if there was any significant archaeology under the surface.
The combined team undertook a comprehensive geophysical survey of the field using magnetometry, resistivity and ground-penetrating radar (GPR) surveys. The results of all three methods are displayed in the final report.
The magnetometry revealed several likely bonfire sites and some faint but unrelated linear features. The resistivity revealed two curved features, of different sizes, but the most convincing feature appeared to be a filled ditch which lined up nicely with an enigmatic spur which extends from the ditch and bank circuit of the hillfort on its western side. The GPR showed a regular gridwork of lines, some especially strong and parallel to the south-eastern edge of the field – though all were shallow.
CONSIDERING THE EVIDENCE
Most of the revealed features were not clear enough for positive identification. The most convincing was the filled ditch in the south corner of the field, which may be an extension of the hillfort's earthworks.
The grid-lines revealed in the GPR results are the most likely match for the patterns in the grass previously seen by the owners during early-morning dew, snow and frost. But their pattern does not easily resolve into buildings, and the radar response shown them to be shallow. Unlikely therefore to be building foundations; more likely to be field drains.
Tantalizing hints and some possibilities, but in general a little disappointing.
Read the full report:
SURVEY BY MEMBERS OF THE BAS ACTIVE ARCHAEOLOGY GROUP, CHESS VALLEY ARCHAEOLOGICAL AND HISTORICAL SOCIETY AND THE COMMUNITY ARCHAEOLOGY GEOPHYSICS GROUP, LED BY KRIS LOCKYEAR
REPORT BY KRIS LOCKYEAR