Recent LiDAR analysis has indicated that the Antonine Wall was 42 Roman miles (some 62 km) long (Hannon et al 2017, 453–5), though the precise location of its eastern end remains uncertain. Its primary linear features were a turf rampart on a stone foundation, a deep and wide ditch to the north, an upcast mound to the north of the ditch (containing material excavated from the ditch) and a road, known as the Military Way, to the rear, connecting the military installations.
The material used for the rampart varied along its length (Keppie 1974; Keppie 1976, 77–8; Romankiewicz et al 2020, 129–33). Although probably originally intended to be built in stone (Hodgson 2020), it eventually came to be constructed for the most part of turf blocks. This apparently was the preferred material, but mixed earth or clay, revetted by turf or clay cheeks, was variously used to the east of Watling Lodge. The rampart was underpinned by a stone base formed of dressed kerbs retaining rough boulders or cobbles. This varied in width from around 4.3–4.9m and appears to have been designed to be 15 Roman feet wide (4.4m). Culverts through the Wall, defined by dressed stones with a flagged floor and capping, have been located at quite frequent intervals, as close as 15m (Keppie 1976, 74–6). In conjunction with the culverts, the base seems to have been provided primarily to facilitate drainage both within and across the rampart to minimise erosion and frost damage (Romankiewicz et al 2020, 123–9). Excavation has occasionally revealed repairs necessitated by damage to the superstructure, possibly from a build-up of water, as at Tollpark, Bantaskin and elsewhere (Keppie 1976, 68–76; Keppie and Breeze 1981, 239–40 and 231–45; Romankiewicz et al 2020, 133–7). No evidence exists for the way in which the Wall negotiated river crossings, but at stream crossings both large culverts and probable supports for a wooden bridge are attested (Bailey 1996).
Nowhere does the rampart survive to a height of more than 1.8m, and the largest number of turf lines recorded in section is 22 (Steer 1957, fig 3 – though the associated text suggests only 20). Combined with the fact that a turf or clay-revetted rampart must be battered to maintain structural stability, this would suggest a minimum rampart height of around 3m (Keppie 1976, 77; Hanson and Maxwell 1986, 81–3). There is no evidence to indicate how the rampart was completed at the top, though most reconstructions assume a walkway and palisade. A single posthole within the body of the rampart at Mumrills could be interpreted as a support for a palisade (Bailey 2021; 315–16, 353). Allowing for the rampart batter, provision of a walkway five Roman feet wide would make 3m the maximum height achievable.
To the north of the rampart lay a wide and deep V-shaped ditch, which is often the most impressively preserved structural element of the Wall. At its consistently greatest size, between Bantaskin and Bar Hill, it was around 12.2m wide and 3.7m deep. Both to the west and to the east of this stretch, however, the ditch was smaller, though no less than about 6m in width (Keppie 1974; Keppie 1976, 76).
The berm between the rampart and ditch varies in width from a norm of around 6m to 9m, the increase often mirroring the reduction in ditch width (Keppie 1976, 76). Wider berm widths are recorded in areas, such as Croy Hill, with more complex topography. At various places along the eastern half of the Wall elongated rectangular pits have been located on the berm (eg Bailey 1995; Woolliscroft 2008, 142–5 and 162–3). Usually, three or four rows have been recorded, set in a quincunx pattern, the most celebrated group, which are still visible today, were recorded at Rough Castle in the excavations of 1902–3 (Buchanan et al 1905). On analogy with more numerous examples from Hadrian’s Wall, they are generally considered to have held thorny branches rather than upright, sharpened stakes.
The material from the ditch was tipped out onto the north side, creating a low, outer mound that served to heighten the counterscarp of the ditch (Keppie 1976, 76; Hanson and Maxwell 1986, 77). The upcast was usually spread out to about 150% of the width of the ditch, but where the ground to the north sloped away it was piled up to a crest forming a substantial barrier in its own right. A small marking-out bank and a line of boulders have been recorded on the north lip of the ditch (Breeze 2014, 22) and it has been noted that the turf was not always first removed from below the mound.
Research issues
- Determine the precise location of the linear barrier where it is currently uncertain, especially segments of the stone base of the rampart.
- Take any opportunities to investigate further the turf and earth construction of the rampart, and the character of any superstructure.
- Take any opportunities to examine the berm for further pits.
- Encourage the publication of small-scale excavations along the line of the Wall in regular collections, as in the past (see Research and methodological issues).
- Seek evidence for river crossings, harbours and related installations.