The Archaeology of the Forest of Dean and the LiDAR System by Jon Hoyle
The Archaeology of the Forest of Dean and the LiDAR System
Jon Hoyle, Senior Project Officer of Gloucester Archaeology Service
Meeting of 13th June 2013
Very little of the archaeology of the area under the trees is known but we know there must be something there: Aerial photographs from the war show sites where forest had been cleared. Worked flint is found regularly. We have several standing stones like the one near Staunton – Bronze Age ritual monuments that usually have a settlement nearby. There are four Iron Age hillforts (Welshbury – well worth a visit, Lydney Park (the Roman temple is inside it), Symonds Yat and Lancourt), so there should be other Iron Age settlements.
Unable to use normal archaeological survey methods, Light Detection And Ranging was used for the first time on a large scale (278km²) in 2006. Lasers are fired from a plane and differences in the speed of bounce back are measured. We saw a fascinating LiDAR image of Bicknor Church and castle area, showing the castle remains to be a more regular shape than that shown on the maps.
1,700 new sites were discovered and recorded, including previously unknown tramways, quarries and over 1,000 charcoal burning platforms (some of which may be Roman). Four sites were examined in more detail with some excavation:
1. Sub-circular enclosure at East Wood, Tidenham: this showed from above as an almost perfect circle 15m across with a mound in the middle. Nothing could be seen from the nearby path, getting up close a low bank was found and then some small standing stones. The mound turned out to be a pile of logs! This seems to be a Bronze Age ring cairn, very like ones around the Brecon Beacons and would have had a similar use to stone circles. The number of sites of this age around Tidenham Chase led to the conclusion that this may well be a Bronze Age ritual area.
2. Sub-rectangular enclosure on Ruardean Hill (one of four such rectangular sites, about 40m across with rounded corners). A huge ditch (about 2m deep) would have been matched with a 2m high bank inside it (the ditch has since been refilled with the bank material). Pottery dated this to Late Iron Age or very early Roman period. This seems to be an early Roman military fortlet, probably an outpost from Gloucester. A Roman century could have built this in about a day, with timber palisades and wood huts or tents. The fort may have been to protect lines of communication for the push into Wales or to control the iron industry in the Forest which was already recognised as important.
Around two centuries later the site was occupied again, with good quality Roman pottery, a saw blade and evidence of iron-making found. This slag is very distinctive and the flow pattern in the metal can still be seen from when slag was let out (tapped) from the bottom of the bloomery – so it is called ‘tap slag’. In the medieval period clay bloomeries were still used. Itinerant smelters travelled a 10 to 15 year cycle between charcoal sites following the coppice felling and carrying the iron ore with them. (Before this LiDAR work only five Romano-British smelting sites were known in the Forest, it looks like there is much more to find).
3&4. Prehistoric and Roman period field systems, showing up as terraces. They were dated by pottery, radiocarbon dating on charcoal and optically stimulated luminescence (which assesses when sand particles were last exposed to the sun). Slag was found here showing iron making in the early Roman period. Where there are fields there must have been homes, and presumably this area was not wooded at the time it was used for growing. Three small enclosures are known of that probably would have held one family in a few huts. There are also field systems around Westbury hillfort . CS