Environmental Archaeology

Sampling at Testwood LakeSampling at Testwood LakeIt is not just the objects that tell us about Testwood in 1,500 BC: environmental archaeologists can get clues from the past by analysing the remains of plants, insects and other organic remains.
The image their work conjures is one of a country idyll: the river at the time was largely freshwater, flowed slowly, was slightly brown in colour from peat in the water and had large shallow areas on its edges, though the centre may well have been deep.
Close to the river, possibly on its banks, grow scrub and small trees. The ground near the river is marshy, with rushes and long grass. As we move away from the river, we find open grassland, and by the time we are half a kilometre away we are in a mix of ancient woodland and fields where cows and sheep graze. It is likely that the cattle was brought to the river to drink.
3D Visualisation of the environment around the earliest bridge3D Visualisation of the environment around the earliest bridgeWe know all this because some species of insects and plants will only live in certain types of environment. For instance, the water buttercup, whose remains we found at Testwood, will only survive in rivers which have shallow edges. Ants which were found at Testwood live in the hollows of rotting trees. The dung beetles we found needed cow or sheep pats to live on.
Environmental archaeologists work on samples taken from the ground at various points on a site. These are put in water; some of the organic matter will float and can be collected, while the rest will sink, as will earth and stones. Sieving of the residue can recover more organic matter.
Alder cones found at Testwood. Scale is in millimetresAlder cones found at Testwood. Scale is in millimetresThe organic matter is then examined under a microscope. This could be plants or insects that have survived because they are waterlogged, such as the water buttercup at Testwood, or because it was charred when a fire was lit – burnt matter survives more easily. Some specialists concentrate on insects, often having to identify a wing or thorax from among millions of species.
"The work is laborious and time-consuming,” said the head of Wessex Archaeology’s environmental archaeology section. “The analysis of the Testwood samples has taken thousands of hours and we’ve used ten specialists who are national experts in their fields. But it’s worth the effort to meet the challenge of reconstructing the past and painting a picture of the landscape and animals that lived there in 1,500BC.”
It’s not just specialists in Britain who work on the samples: a small part of the cleat from the boat will be sent to a laboratory in New Zealand for carbon dating.