Roman camp and Gask road excavations, Perthshire, 2007
D.J.Woolliscroft, University of Liverpool
West, which sits directly across the river from the fort and might, like others of the same series (e.g. Marcus), have an annex. The second is the still larger, 130 acre camp of Innerpeffray East. The frontier road runs just to the north of the latter on a near parallel line (Woolliscroft & Davies, 2002) and a well preserved length of both it and the camp defences can still be seen in Parkneuk Wood, along with a Gask series watchtower (NN 917185). It has long been known from air photographic evidence, however, that the road passed through the 63 acre camp. Moreover, rather than entering and leaving at a gate, it runs straight through the defences, on either side of their NE corner, which suggests that the two were not built at the same time and can never have operated together. Neither feature has produced firm dating evidence, despite the fact that the road has been investigated on numerous occasions. Indeed it has been excavated twice by the Roman Gask Project in this same vicinity: once in Parkneuk Wood (Woolliscroft & Davies, 2002) and once just south of Innerpeffray Library, where it runs up from the Earn in a massive cutting (Woolliscroft 2005). Nevertheless, the likely construction sequence appeared obvious. It seemed probable that the road was built first, because it was assumed to belong with the later 1st century frontier works, whilst the 63 acre camp group was thought to belong to the early 3rd century Severan invasion (e.g. Reed 1976, 95ff & Hanson 1978, 146ff), or, possibly, to the mid 2nd century Antonine occupation.
The excavation
The more westerly of the two points (fig 1) where the road crossed the camp perimeter (NN 9079 1840) lay beside a field track, which facilitated access and made it easier to locate the intersection precisely, and excavations were undertaken in August 2007. The work was directed by the writer on behalf of the Roman Gask Project and was crewed by volunteers as part of Perthshire Archaeology Month. The trench was roughly located using an air photo rectification prepared by the RCAHMS, but to further check the exact point of intersection a geophysical survey was conducted. This failed to find any error whatever in the RCAHMS plan and thus allowed a small trench of just 1m (e-w) x 10m (n-s) to be used with confidence.
Once the topsoil (fig 2, context 1) had been removed, the ditch top was clearly visible as a damp, almost stone free grey/brown loam (c3). Its southern edge was clearly defined, cut into a natural subsoil of gritty buff coloured clay
(c2), but the northern edge was initially more difficult to identify. Instead, the plough damaged remains of the road surface were visible as a mixed spread of rammed gravel set in a matrix of dark brown clay and loam (c4) and dark buff clay and loam (c6) up to 160mm thick, which contained a few larger fist sized cobbles. There was also a single topsoil lens (c5) where a larger flag of c. (0.22m)2 had been ploughed out of the structure. These deposits continued beyond the northern end of the trench, but were 4.46m wide within it. The road proved to have encroached over the in-filled remains of the camp ditch and had subsided somewhat into it.
Once fully revealed, the ditch proved to average 3.78m wide and had a shallow 'V' shaped profile, which was noticeably steeper on the northern (outer) side than in the south, in the manner of a so called 'fossa punica'. Its full depth could not be determined as it had been followed by a modern land drain (c13) which blocked the centre line and caused flooding when any attempt was made to dig to a lower level beside it. As a result, all that can be said with certainty is that the ditch was excavated to a depth of 1.2m below the modern surface, although an extrapolation of the known sides would suggest a total depth in the order of 1.5m.
The bottom fill of dark grey silt (c9) was surprisingly thin (60mm max) and did not get thicker with depth, as one would expect of an undisturbed layer deposited under gravity. It thus gave the impression of having been cut into, perhaps by a re-cut or cleaning operation. Above this lay layers of plumb grey (c11) and pale brown silt (c17), overlain by pale grey (c10) and grey/brown loamy silt (c16). These had been truncated at their top, perhaps by plough action, and then overlain by very different, less silt based layers: a smooth pale grey clay with large inclusions of orange clay (c15), grey/brown silty clay (c18) and smooth mid grey clay (c8). The latter was then overlain by the road (c4), which thus post-dated all of the activity to date. This in turn was overlain by orange/ brown clay (c14), a small lens of greasy grey material which appeared to be degraded turf (c12), the grey/brown loam of the ditch top as initially seen (c3) and finally by the current plough soil. The modern land drain slot had been cut from below the level of c3, suggesting that this was of very recent formation.
Lastly, a shallow, irregularly shaped pit, filled with rusty brown grit and sand (c7) was encountered under the road, just to the north of the camp ditch. It was far from clear that this was an archaeological feature at all and it may represent the decomposed remains of a large piece of sandstone.
No datable finds were recovered, except for two sherds of modern glass and a plant pot fragment from the plough soil.
Interpretation
The road clearly post-dated the camp ditch, possibly after the latter had been cleaned out (presumably for a second (or as part of a single prolonged) usage) and certainly after it had silted to a considerable depth. Contexts 8, 15 and 18 may then have been deliberately deposited (c15, in particular, was highly mixed) and might represent an attempt by the road builders to completely obliterate this part of the ditch to provide a level construction surface. The backfill later settled, however, taking the road's southern edge with it. This was a wholly unexpected sequence with obvious dating implications for, as already mentioned, it had previously been assumed that the road would be of 1st century date and the camp significantly later.
Given the new circumstances, a number of possible scenarios present themselves. The first is that the 63 acre camps might, after all, date to the 1st century and represent the campaigning phase of the first Roman invasion, whilst the road forms part of later consolidation activities, which included the construction of the Gask frontier. This does seem unlikely, however, for although these camps are undated, work on the example at Ardoch has shown that it came late in the sequence of several overlapping camps to the north of the Roman fort (St.Joseph 1970, 163ff). A second possibility is that the road is Severan, or even post Roman, but this too seems improbable: especially the latter. Unlike the Flavian and Antonine periods, no forts are known to have been occupied in this area in Severan times. Instead, the main centre lay away from the Gask road at Carpow on the Tay estuary. There was thus nowhere for the road to be going and it seems improbable that a well engineered, all weather highway, with cuttings, embankments and other major works, would have been built here at this time when it had not been earlier. Likewise, few engineered roads of this calibre were built through this region in post-Roman times before the 18th century, a period from which good documentation survives, which would certainly record construction on the scale of the nearby Innerpeffray cutting. Moreover detailed estate maps exist to show that the road was out of use and invisible by the 19th century, when the lane to Innerpeffray Library was already following its current line and lay c.130m to the north (pers com C and A Edgar). The road's structure is admittedly slightly unusual for Roman roads in general and even for the Gask road in particular, in that it consists only of a rammed gravel and cobble layer on this site, whereas elsewhere it was founded on a layer of larger stones and sometimes a turf agger (Woolliscroft & Davies 2002). Nevertheless, there are parallels on the Gask, including the road bed found in the Innerpeffray cutting (Woolliscroft 2005) and that passing the camps at Ardoch (St.Joseph 1977, 139 and Glendinning & Dunwell, 2000, 262ff).
Perhaps the most likely scenario is that the camp and the Gask road as we see it today are both Antonine. It still seems probable that the 1st century frontier would have had a road of some kind, and the fact that the entrances of its towers and fortlets are all oriented on the known road would suggest that it followed a similar line. But it is perfectly possible that this primary road was little more than a light track that was only replaced by the current engineered line during the Antonine period, when the three Gask forts of Ardoch, Strageath and Bertha, came back into use as outposts of the Antonine Wall, possibly for longer than their original occupation. This would have allowed a greater emphasis on wheeled traffic, especially as a number of cuttings and embankments were built to ease gradients, whereas the 1st century phase may have been designed more for foot and animal traffic (perhaps including pack animals). If so, the camp might represent the Antonine re-invasion of the area, whilst the road formed part of the subsequent consolidation. None of this can yet be proven, but the dating of the known Gask road has certainly been questioned before. Indeed the writer pointed out some years ago that a road quarry pit dug through the entrance of the Gask tower of Shielhill North seemed incongruous if the two were supposed to be contemporary (Woolliscroft 2002, 75f). Moreover, this dating would help to explain two phenomena that have long presented something of a mystery. The first is the fact that the road appears to end at Bertha on the Tay, rather than running on to the legionary fortress of Inchtuthil. Inchtuthil was much the most important installation built during the Flavian occupation and, for both logistic and strategic, reasons it has always seemed hard to understand why the road did not go there. The site was not reoccupied in the Antonine period, however, and there would thus have been no reason for a 2nd century road to include a site that had been abandoned over half a century before. Secondly, the apparent lack of a network of similarly well constructed roads to link the Gask with the so called "Glenblocker" forts to its north has also posed something of a puzzle. Again, however, these had long been long abandoned by the Antonine period and only one, Dalginross, has yet shown evidence of reoccupation (Woolliscroft 2002a, 40f). Properly constructed stub roads can be seen from the air emerging from some of their gates, which suggests that engineered roads had been planned to link these sites to both the Gask and each other but, in the event, these were never built. It is remains perfectly possible, however, that lighter 1st century tracks were laid down as a temporary expedient, perhaps consisting of little more than hard-core spreads, but these could easily have been ploughed away in later times to the point of being archaeologically undetectable.
Acknowledgements
The writer is grateful to the landowner, Mr C.R.Connell for access to the land, to the Perth and Kinross Heritage Trust for funding, to Peter Morris and David Hodgson for help during the geophysical survey and to the excavation volunteers, who worked long and hard in an often flooding trench.
Bibliography
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