Hertfordshire NMP

Hertfordshire was mapped from aerial photographs as part of the cropmark classification project organised jointly by English Heritage and the Royal Commission on the Historical Monuments of England (RCHME). As such it was one of the four pilot projects for the National Mapping Programme (NMP). As a pilot survey, the methodology for the Hertfordshire project differed somewhat from that subsequently developed for the NMP in that earthworks were omitted; only cropmarks were plotted. This meant that for nearly one third of sheets covering the county there are no recorded sites (see project area). Likewise most sites were transcribed from specialist oblique photographs and vertical photographs were only consulted when they provided information about known sites that could not be recovered in any other way. 

The geology and soils of the county are varied which affected the recovery of archaeological information from aerial photographs. In the north there are chalk uplands forming an eastern extension of the Chilterns, on which numerous archaeological sites have been recorded whereas much of southern Hertfordshire is dominated by stagnogleyic soils largely unproductive of cropmarks. Nevertheless the project recorded a number of sites of various dates and functions, and subsequent photography of the county has revealed more.

Amongst the features recorded are sites ranging from cropmarks of large enclosures of presumed prehistoric date to traces of possible medieval garden landscapes seen as parchmarks.

Because it was a pilot project the results were not published in a report in the way that has since become standard practice and there is probably a lot more analysis that could be carried out. 

The images used on this page are copyright English Heritage unless specified otherwise. For further details of any photographs or other images and for copies of these, or the plans and reports related to the project please contact the NMR English Heritage's public archive.

For further information on a project or any other aspect of the work of the Aerial Survey team please contact us at: AerialSurvey@english-heritage.org.uk.