Aerial Reconnaissance in England 1994
Featherstone, Roger, Antiquity
The summer of 1994 in Britain started cold and wet, with the spring growing season distinctly late, and then turned very hot. Each summer, with its own personality, makes for a different flavour to the air photography.
The Air Photography Unit of the Royal Commission on the Historical Monuments of England (RCHME) has been undertaking aerial surveys itself since 1967 (Hampton 1989), and since 1986 grant-aiding regional aerial reconnaissance for archaeology in England. Reports in ANTIQUITY (Griffith 1990) have presented the results of recent good crop-mark years. This note is a rapid assessment of the short but very successful 1994 summer flying season; (L)25,000 allocated to the regional reconnaissance programme augmented the RCHME's own flying from bases near its offices in Swindon and York.
The primary objective of the reconnaissance is to enhance our archaeological knowledge by discovering new sites and learning more about old ones. Although this report concentrates on crop-mark discoveries, the reconnaissance programme also includes earthworks, soil-marks and buildings, especially hospitals, farms, textile mills and industrial-archaeological sites.
Despite prolonged wet weather at the beginning of the year, increasing dryness from May onwards caused soil moisture deficits to increase significantly over much of central, northern and eastern parts of the country (although East Anglia had a surprisingly poor crop-mark season). The production of crop marks in 1994 was due not only to the dryness but also to the high summer temperatures which together induced greater stress on the crops when they were growing most quickly.
In southern England, from June onwards, good crop marks were developing in soils over the limestones (in the Cotswolds), chalk areas of Wessex and the gravels of the middle and upper reaches of the Thames and its tributaries, as well as in parts of Bedfordshire, Buck-inghamshire and Essex. Northern England had good crop-mark conditions in the Vale of York, on the chalk Welds, Holderness, Howardian Hills, as well as on the Tabular Hills on the southern edge of the North York Moors; during July Northumberland became probably the driest area in the country.
RCHME staff in Swindon and York flew approximately 260 hours between April and the end of August and recorded more than 2000 sites. Regional flyers carried out a further 190 (estimated) hours of reconnaissance of which about 60 were flown in Northumberland alone by Tim Gates.
A primary objective of reconnaissance in years when crop marks are good is to search for new sites in previously unproductive or inaccessible areas. On one RCHME flight in the area around the recently closed military air-field of Upper Heyford, Oxfordshire, 75% of sites photographed were new discoveries. Amongst these were a number of Iron Age 'banjo-type' enclosures, including a group of three in one field alone, and the four rectilinear enclosures on FIGURE 1.
The need for continuing reconnaissance over areas subjected to fairly intensive survey, in many cases for more than 60 years, is also clearly demonstrated this year. On flights over an area of the Thames Valley recently mapped in RCHME's National Mapping Programme (NMP), 57 separate sites were photographed, of which 13 were new and a further 27 yielded significant additional information. A good example is the defended settlement known as Dyke Hills near Dorchester-on-Thames. Here a large field re-seeded with grass at a critical time revealed that the settlement was more extensive and far denser than it appears on earlier photography.
Other notable new discoveries in the south were a new Neolithic causewayed camp near Burford, Oxfordshire, and an enclosed Roman villa near Ludlow, Shropshire. One of the most surprising was a small Roman marching camp beside the Roman road of Akeman Street near Burford, situated next to a rectilinear enclosure, presumably of a late Iron Age date. …