RAF Glass Negative

One day in July 1923, OGS Crawford, Archaeology Officer at the Ordnance Survey, was at RAF Old Sarum to look at their collection of small glass negatives containing aerial images captured during training flights. One set, taken on June 15th 1921, showed – very faintly – two parallel white lines in a field northeast of Stonehenge. Crawford suspected that these represented traces of the Stonehenge Avenue, whose course beyond King Barrow Ridge had previously been a matter for speculation. Crawford tested his suspicions through excavation in September 1923, demonstrating that the white lines represented buried ditches. This, the first cropmark to be identified on an aerial photograph, the first clear proof that aerial photography offered a means to discover unknown sites, allowed Crawford to connect Stonehenge to the River Avon, and to suggest that the Avenue was the route along which the bluestones were hauled for the final part of their journey to Stonehenge. Contributor: Martyn Barber (Historic England)