Bocastle Roman Fort Geophysical Survey

Date 2006

Event ID 551500

Category Project

Type Project

Permalink http://canmore.org.uk/event/551500

NN 614 079 Resistance and magnetic surveys were conducted over the entire fort and its surroundings. The results contradict various unusual features described in the report on the excavations in the 1950s (1). The survey confirmed aerial evidence of a double ditch circuit with 'parrot beak' gate breaks. The NW and SW corners had survived encroachment by the River Teith and a railway cutting. Despite the excavators' claims to the contrary, however, the NE corner had been eroded by the river. More importantly, the magnetic survey detected clear foundation traces for some of the main range of buildings, whereas the excavation claimed that the interior features had been destroyed by an incursion of the river. The site is thus significantly better preserved than had been thought. One aspect of the excavation plan was strikingly vindicated, however, for the rampart showed deep (up to 26m) re-entrants at all four gates. These fit well with the parrot beak ditch breaks and would have formed an enfiladed killing ground in front of the gates.

The survey confirmed air photographic hints that the fort and temporary camp ditches might intersect. The two thus seem unlikely to be contemporary. The upcast from the fort ditches obscures the camp ditch where the two cross, which might suggest that the camp was built first. Trenching was conducted on the camp's W defences to determine which of three possible ditch lines, seen from the air, was the real camp ditch. All proved to be V-shaped ditches and two had been re-cut. No dating evidence was recovered to prove that all were indeed Roman, but if so they would suggest a complex occupation history. On the other hand, trenching close to the camp's SE corner demonstrated that an aerial feature which had seemed to be an annexe was natural in origin. Here, however, more modern traces of metalworking were found, including iron blooms, furnaces and furnace waste.

Two other post-Roman features were surveyed; a group of lime kilns to the W of the fort and a large oval stone revetted platform in the centre of the camp, which had been cut into during the construction of the modern Bochastle farm.

Sponsor: the Roman Gask Project.

D J Woolliscroft and B Hoffman 2006