Launch of new archaeological features map

Background

In 2000 I moved from interpreting remotely sensed imagery of tropical locations to the more mundane Kent natural habitats. Surprisingly I found a great many unrecorded archaeological features visible in the project aerial photography. One of those “finds” a nondescript feature in cricket pitch at Bourne House, was taken up by the Cambridge Classics and subsequently proved by geophysical survey and test pits to be a Roman Villa. A revelation that set me off on a road upon which I am still travelling, mapping Kent archaeology.

Kent was the first county completed by the Royal Commission on the Historical Monuments of England mapping programme in 1988 largely based on the oblique aerial photography taken by J K St Joseph who pioneered this form of archaeological research. Oblique photographs were notoriously difficult to map in vertical plan with distorted shapes and inaccurate geolocation (see image below of RCHME cropmarks and modern imagery). I was tasked with using the latest digital technology to remap the earlier work and to add all the new features visible in the dozen or more county wide aerial surveys flown since 1989.

Aerial photograph showing two areas of cropmarks, highlighted black.

Much has changed since 1989 with new remote sensing platforms. LIDAR with the ability to show terrain normally hidden by vegetation and geophysical surveys for mapping subsurface features. Historic maps and plans became available in digital formats and finally plans of archaeological excavations.  The new mapping draws on all these sources to construct a new digital database.

Whilst some Kent defences show as cropmarks, notably slit trenches, the two most valuable sources are the old War Office plans and the 1944-46 series of aerial photographs. The former were digitsied and added to the database and the latter are excellent sources of long lost structures but also for the more ephemeral features like barbed wire entanglements.

Example

An example from the database of Shornemead Fort is shown below. Structures in yellow and earthworks green and in this instance barbed wire entanglements are orange. The main fort is digitized from the War Office plans. The Mine Warfare buildings, pillboxes and barbed wire from the 1946 aerials. The emergency battery and the craters from the 1961 aerials and the flood defence bunds from the 19th Century OS maps and the modern LIDAR 1m resolution terrain model.

Examples of mapped features, coloured by layer.

The fort floor levels are digitized as separate but superimposed layers. Different phases of structures like Roman Villas are handled in the same way. The downside of this you do need the right software to unravel it all. With only fifty percent of the county complete, by the time I have finished there may well be an online “app” to do just that.