Geophysics has been used at a site in the Fens to pinpoint the exact site where a Spitfire crashed in November 1940. Last month, Peter Masters, Research Fellow at Cranfield University, Forensic Institute undertook the geophysical survey of the field where the Spitfire reportedly crashed and the pilot lost his life.
The geophysical survey was carried out to pinpoint the location of the aircraft and has revealed what we hope will be a well-preserved engine around two to three metres below the surface. A metal-detecting survey was also carried out by local volunteers.
This will ensure that an excavation, scheduled for later in the year, is conducted in the correct area so that the team of archaeologists can unearth the plane from layers of peat and clay.
Two techniques were used – a magnetometer – a device with two vertical white poles (sensors) connected by a horizontal pole, looking like a small rugby goal post. The horizontal bar includes a small box which collects and stores the data. The machine (so sensitive that operators must wear clothing without metal zips, buttons etc) is used with a harness around the body to support it, holding the machine in front of the wearer while they walk up and down the designated area taking readings.
The designated area was mapped out into 20m grid squares; within this the operator walks the lines of the grid 1m apart to cover the whole area; readings measure small magnetic changes in the soil, detecting up to 3m below the ground, identifying subsoil which differs from top soil because of its magnetic content, in areas where the ground has been disturbed.
Ground Penetrating Radar was also used to give additional information: an electromagnetic energy signal is pulsed into the ground up to 40m deep. The penetrating waves transmit and receive at a rapid pace through the sub-surface; the unit measures the strength of the returning signal. The pulses are sent and received in real time creating a ‘slice’ of information that can be seen on a monitor simultaneously. When the data is collected and processed on the computer a 3D image can be created of the surveyed area.
The archaeology team working on the excavation are from Oxford Archaeology East, based at Bar Hill, Cambridgeshire and will also involve the Great Fen Archaeology Group and members of Operation Nightingale: founded in 2012 to utilise both the technical and social aspects of field archaeology in the recovery and skill development of soldiers injured in the conflict in Afghanistan. The Great Fen project partners: The Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire, Natural England, the Environment Agency, Mid-Level Commissioners and Huntingdonshire District Council will be following the dig and any finds (which will go initially to RAF Wyton) with keen interest.