Bronze Age clues
- Using aerial images to define a local burial mound
- Exploring how crop marks can reveal underground structures
We had learnt that our village's name was derived from the burial mound of a Bronze Age warrior, Trippa. This mound was no longer visible as it had been flattened during the Napoleonic Wars when arable land was desperately needed.
We were keen to identify its original location. To help me do this, I was given a ride in an Auster aeroplane by its owner, David Miller, whom I had met when giving a history tour of Thriplow. We took off from Duxford Airfield and I took a beautiful aerial photograph of the Bronze Age site, revealed as a crop mark in growing wheat.
'Dowsing rods can be made of metal such as old coat hangers or hazel ...'
Crop marks show features below the ground. They are revealed by a change in colour or height of the growing crop such as wheat. If there is a ditch below the ground then the crop will be greener and higher than the surrounding plants. If there is a wall or building below the soil this will stunt the plants and cause them to ripen more quickly and show up as a paler mark on the aerial photo.
In 2000, the group asked Dr David Trump, who excavated the tumulus in 1953-1954, to talk to them about his finds. At first, he had not been able to locate the precise site - field boundaries had changed so much in 45 years - so he had got out dowsing rods.
Dowsing rods can be made of metal such as old coat hangers or hazel; they work by interrupting the earth's magnetic field to reveal anomalies below the soil. The site proved to be just where the subsequent aerial photograph showed it.
I talked to the landscape archaeologist Dr Christopher Taylor about the origins of the parish as other interesting sites appeared from aerial photographs which we then traced onto maps. This revealed a Roman villa just over the border in Whittlesford parish. The existence of this had always been known about as painted pottery and tiles had been found in the soil, although the area is yet to be excavated.