Croghan to Kiltober

The landscape between Croghan and Kiltober is dominated by limestone till and cutover bog, with rock on the hills and occasional alluvium in the lowlands, but the western side is made up of limestone sands and gravels with a very substantial esker (Fig.

Fig. 6.6 Croghan to Kiltober Least Cost Path and soils

ringforts in the Medieval period, particularly in areas with limestone sand and gravel subsoil, west of the esker.

Clonearl Bog and Raheenmore Bog are located between Croghan and Kiltober, and these must be negotiated to move between the settlements. A series of low hills lie between Croghan and Kiltober, at Oldcroghan, Kilduff, Clonagh and Mul- lagharush Hill, which flank the narrowest points of the bogs.

6.5.1 Least Cost Path Results

The Least Cost Paths for this segment similarly traverse the bogs at the narrowest points available without deviating course more than a few degrees (Figs. 6.6 and 6.7). Clonearl Bog is crossed at the narrowest point, which is defined on the east side by a rise in Oldcroghan, and on the west by Kilduff Hill.

Fig. 6.7 Croghan to Kiltober

6.5.2 Agent-Based Modelling Results

The journey from Croghan to Kiltober requires the crossing of Clonearl Bog and Raheenmore bog. The leader finds the narrowest points in these bogs, which is the same as the crossing points suggested by Least Cost Paths (Fig. 6.7). The model deviates from the ArcGIS version on the western extent where the esker is accessed. The model does not include in-built preference to the esker subsoil type, but is controlled in this context by slope. The leader, when moving from east to west, does not move northwest to climb the esker, as the Least Cost Path model shows, but crosses the esker much closer to the target. The final follower crosses the esker 132 m from where an existing road transects the esker. This coincides with a slight drop in the contours east of the esker, which naturally direct movement to this point.

6.5.3 Archaeological Evidence

Clonearl Bog is most recognised for the Iron Age bog body found there in 2003. Oldcroghan Man, as he is known, was found 1.3 km southeast of the proposed crossing, where the bog is at its widest (Plunkett et al. 2009). As discussed above (Sect. 6.2.2), activities in the bog can be separated between those which treat the bog as an obstacle and those which treat it as an objective. The deposition of Oldcroghan Man was a ritual activity and it is no surprise that it should take place in a different location to simple negotiation of an obstacle.

The archaeological evidence in this segment is minimal. The paths pass a ring barrow in Oldcroghan and do not encounter any further known archaeology until in view of the esker. The most compelling evidence supporting the potential paths is their similarity to the existing road network. The predicted paths closely correlate with existing roads at the Raheenmore Bog crossing and along the southern slopes of Clonagh and Mullagharush Hill. The paths from both models are very similar in this segment. Except for the more obvious deviation on the western extent, they follow the same general corridor of movement with paths separated by a maximum distance of only 250 m. It is clear that major obstacles, such as the bogs, produce the most uniformity between the models and the existing road network.

The Rahugh esker is associated with a flanking road on the east side, and the presence of two castles along its course suggests the esker itself was used as a path in the Medieval period, with the earlier of the castles dating to the late 12th or early 13th century. A standing stone sits 220 m from the esker, which implies a signif­icance to this landscape feature in prehistory also. The linear nature of the esker makes it an ideal feature by which to maintain orientation and to pilot by. Travelers can rely on such a feature to plan movement from a distance in this fashion, but it also acts as a suitable surface to walk over. The height which it offers provides a means of seeing some distance and planning a journey accordingly, while also being well-drained and linear.

6.6