Doncaster's hidden heritage

Crops, aerial photographs and Doncaster's hidden heritage

Views from the air and crop marks

Many of Doncaster’s Iron Age and Roman sites do not survive above ground because of centuries of ploughing and development. The extent of this hidden heritage was first revealed by archaeologists who flew over the region between the 1940s and 1970s. Vast buried landscapes came to light from the air, visible as cropmarks. These otherwise invisible ancient worlds were revealed by the crops that grew above them, because crops tend to grow taller over the deeper soils that fill ditches and shorter above the foundations of walls. Once photographed, the features revealed by the crops’ growth could be drawn on to maps and the full extent of these cropmarks plotted.

The Roman fort at Rossington Bridge

The Roman fort at Rossington Bridge was one of the first sites to be photographed, in the 1960s. The true extent of the cropmarks began to be identified during the 1970s, when archaeologist Derrick Riley flew hundreds of missions. While piloting one of Sheffield Aero Club’s small planes he took photographs of the cropmarks with a hand-held camera. He discovered a regular pattern of square and rectangular fields, seen as the lines of boundary ditches dug to enclose the fields. Most were arranged into 50 to 100 metre-wide strips divided by long parallel ditches, which led Riley to call them ‘brickwork fields’. Other sites could also be seen within this overall pattern. Sometimes two ditches ran in parallel 10 to 40 metres apart, forming lanes which were probably droveways for moving livestock.

Outlines of building foundations were also glimpsed here and there amongst the fields. What Riley had discovered were the vast buried remains of ancient agricultural landscapes.

Iron Age Tribes of the Don

It is difficult to identify the exact locations of tribal boundaries in the Iron Age. Borders may not have been marked on the ground and not every tribe was a single group of people with a central chief. It is only because of the Romans that we have named tribes linked to specific regions. The Roman authorities needed some way of organising their new province. Surviving Roman documents mention two tribes in this area. The River Don may have been the border between these, with the Brigantes to the north and the Corieltauvi to the south. The river later became the boundary between two Roman administrative areas.