Archaeological prospecting in woodland using LiDAR - summary of 2008 surveys

Light Detection And Ranging (LiDAR) surveys are one of our Woodland Heritage Services

Castle Neroche and the Black Down Hills

During the early months of 2008, a LiDAR survey was undertaken as part of a partnership project looking at part of the Black Down Hills AONB on the Somerset/Devon border. The survey area was dominated by a ridge of hills in a east-west orientation with a steep north-facing slope.  The landscape is predominantly agricultural, but with significant patches of woodland. Perhaps the most striking archaeological features shown were the extensive network of banks and ditches forming field and other boundaries. The LiDAR survey showed the majority of these to be significant earthworks, typically topped with ancient trees or hedgerows. Some of the currently wooded areas also contain regular patterns of these banks (some with veteran trees on them) suggesting a former agricultural land use.

Aerial photo of Blackdown Hills forest canopy 
Aerial photo of forest canopy
LiDAR modelled ground surface of Blackdown Hills
LiDAR modelled ground surface

Two hillforts, were revealed by the survey, one partly wooded, the other under full woodland canopy. The promontory fort of Castle Neroche had previously undergone a detailed, ground-based survey of its complex earthworks. Conversely, a simpler, more densely wooded hillfort to the north had not been surveyed and the LiDAR results showed not only the good degree of preservation of the form of the monument, but also more discreet features such as saw or prospection pits within its interior. For both of these monuments, the new data will allow greater analysis of the individual features, but also their relationship within the wider landscape.

Aerial photo of Orchard Wood forest canopy 
Aerial photo of forest canopy
LiDAR modelled ground surface of Orchard Wood 
LiDAR modelled ground surface

Further information on the Castle Neroche Partnership Scheme

Northants Forest District

A small woodland within the Northants FD contained previously known features of Romano-British date, including some structures. A LiDAR survey of the woodland was commissioned to complement some archaeological investigative work (involving both ground-based surveys and trial excavation). The report of the archaeological investigation confirmed the occurrence of a building, the exact function of which is currently unknown. The vast majority of the remains recorded from a ground-based topographical survey were also disclosed by the LiDAR survey. The ground-based survey provided a good mechanism for testing the LiDAR method and showing the effectiveness of the latter. Because LiDAR is a remote sensing technique, it was possible to survey the whole woodland very rapidly, allowing a greater interpretation of the site in the surrounding landscape and its association with other archaeological features disclosed elsewhere in the woodland.

Aerial photo of small woodland in Northants Forest District 
Aerial photo of forest canopy
LiDAR modelled ground surface of small woodland in Northants Forest District
LiDAR modelled ground surface