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Hertfordshire National Mapping Programme project

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), before their merger in 1999. As such it was one of the four pilot projects for the National Mapping Programme (NMP).

Colour aerial photograph showing a number of fields under the plough around buildings making up a farm or small hamlet.
A plough-levelled barrow cemetery near Baldock photographed as soilmarks on 08-SEP-1988 (NMR 4264/01) © Crown copyright. HE

As a pilot survey, the methodology for the Hertfordshire project differed somewhat from that subsequently developed for the NMP in that only sites visible as cropmarks were plotted; earthwork sites were omitted.

This meant that for nearly one third of the map sheets covering the county there were no sites recorded by this project. Another difference to more recent projects is that 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 many sites of various dates and functions, and subsequent photography of the county has revealed more.

Colour aerial photograph showing a number of arable fields with some houses and open grass in the bottom left of the image
A probable prehistoric enclosure near Throcking visible as cropmarks on 24-JUL-1990 (NMR 4657/25 ). © Crown copyright. HE

Sites from all periods

In spite of the fact that the full range of sources was not used for this project it still recorded a large number of remains. These included cropmarks of large enclosures of presumed prehistoric date.

Colour aerial photograph showing an arable field with some cropmarks seen as darker lines against a paler background
Probable prehistoric enclosure near Bygrave photographed on 14-MAY-1990 (NMR 4589/09) © Crown copyright. HE

Continuing reconnaissance

Since the conclusion of the project continuing reconnaissance in the region has identified cropmarks of a number of new sites. Furthermore, traces of possible medieval garden landscapes were photographed as parchmarks in the particularly dry summer of 1995. These included the foundations of external walls, gate piers, and gazebos in the landscape gardens at Hamels Park.

Colour aerial photograph showing a country house with a golf course with bunkers and greens
Remains of the extensive landscape gardens at Hamels Park showing through the golf course as parchmarks photographed on 15-AUG-1995 (NMR 15370/12) © Crown copyright. HE

They also included more enigmatic parchmarks at Aspenden Hall that could relate to the earlier phases of the house.

Colour aerial photo showing a large house under construction/renovation with large areas of parched lawns surrounding it
Parchmarks at Aspenden Hall photographed on 15-AUG-1995 (NMR 15370/09) © Crown copyright. HE

Because it was a pilot project the results were not published in a standard report in the way that has since become standard practice and there is probably a lot more analysis that can be carried out. However, some brief results of the project are presented in the project report.

Crop marks in Hertfordshire

Crop marks in Hertfordshire

Published 1 November 1992

Report from the Hertfordshire NMP mapping project.

The images used on this page are copyright Historic England 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 Historic England Archive.

For further information on a project or any other aspect of the work of the Remote Sensing Team please contact us via email using the link below.

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