High-flying lasers reveal forests' ancient secrets

 

News from Forest Research: July 2007

Laser beams shone down from the sky are revealing archaeological and other treasures hidden in Britain's forests - by "seeing through" the trees. These can include sites of ancient settlements, fortifications, farms and other signs of human activity which, in woodland, are often difficult to detect from the ground or the air with the naked eye.

Called lidar ('light detection and ranging'), the technology works by "bouncing" harmless laser energy off the forest in much the same way as radar ('radio detection and ranging') bounces radio waves off solid objects, and measuring the time it takes for the pulses to be reflected back to the recording instruments in the aircraft.

Further information about LiDAR

Forest of Dean and Savernake Forest surveys

One of the first uses of lidar to find archaeological features in British forests was a survey of 280 square kilometres (108 square miles) of Gloucestershire, including most of the Forest of Dean. Carried out by scientists and archaeologists from the Forestry Commission and Forest Research, Gloucestershire County Council, Cambridge University and English Heritage, it was the largest single heritage survey of woodland ever undertaken in Britain.

A smaller survey of 42 square kilometres (16 square miles) of Savernake Forest in Wiltshire was also carried out to check the accuracy of lidar findings against known archaeological features and veteran trees. This also revealed hundreds of linear and multi-sided features that archaeologists want to check out. And in addition to built structures, lidar is also helping to map the many 'veteran' (very old) trees of Savernake.

Survey results

Continuing research

Forest Research is continuing research with the partners to determine the optimum survey and data-processing parameters to obtain the most information from the current survey method, and testing the next generation of lidar systems.

We will also undertake some 'ground-truthing' of the Dean data to establish the size limits of features disclosed under different vegetation types. The aim of this research is to develop guidelines for others considering this type of survey.

For further information contact

Peter Crow
Forest Research
Alice Holt Lodge
Farnham
Surrey GU10 4LH

Tel: 01420 526168
Fax: 01420 23653
Email: peter.crow@forestry.gsi.gov.uk