1998:125 - CARRICKMINES-BRAY GAS PIPELINE, Carrickmines Great/Laughanstown/Tiknick/Rathmichael/Shankill/Ballyman, Dublin

A number of sites were identified and excavated during the construction of a Bord Gáis Éireann pipeline in September-November 1998. The proposed route of the pipeline ran roughly north-south from Carrickmines to Bray. The townlands that the pipeline passed through included Carrickmines Great, Laughanstown, Tiknick, Rathmichael, Shankill and Ballyman in County Dublin, and Fassaroe, Kilbride, Kilcroney, Wingfield, Hollybrook and Ballywaltrin in County Wicklow.

Previously testing had been carried out by Eoin Sullivan on field systems (Dublin SMR 26:71) identified in Laughanstown/Tiknick townlands (Excavations 1997, 24–5, 97E360). As much of the area contained a stand of mature conifers any potential archaeological remains appear to have been disturbed during ground preparation and the planting of the trees.

In a number of areas narrow (less than 1m wide) roadside trenches were dug for the pipes, while on cross-country sections a c. 10m-wide corridor was stripped for construction. The roadside trenches were generally dug through deposits disturbed during the original road construction. There was no evidence that archaeological remains were disturbed by these sections of the pipelines. Pipes were laid alongside the roadway in Rathmichael townland and for practically all of the County Wicklow sections of the route.

On the cross-country sections six discrete archaeological sites were identified along with a number of early modern field drains. There had been no previous surface expression of any of the sites, which were identified during topsoil removal and then excavated to the limits of the pipeline corridor. The sites included four fulachta fiadh, a hearth of unknown date and a multi-period site that saw three phases of use including one that involved the construction of a wedge tomb.

Other areas of potential archaeological interest were two road crossings over the upper portion of Heronsford Lane (in Laughanstown/Tiknick townlands). As this runs to Tully Church, it may follow the line of an earlier road. It has been suggested that the upland (cross-country) portion of Heronsford Lane (which the pipe-trench cuts) dates to this period. Much of the surface had been eroded in the area of the road crossing and had been subsequently damaged by agricultural machinery. There appeared to be little chance of recovering any information from the two damaged sections.

Carrickmines Great
Fulacht fiadh 32134 22345
The site was originally identified during topsoil-stripping as a 7.5m (north-south) by 6m spread of burnt stone and charcoal in a loose, silty clay matrix (F1). It had been truncated by a field drain running north-south through the middle of F1. A pit (F3) was identified below the eastern portion of F1. It measured 0.95m (south-east/north-west) by 0.7m and was up to 0.42m deep. The pit was full of a deposit of burnt material that could not be distinguished from F1. A flake of struck flint was recovered from the interface between F1 and the subsoil, just east of F3.

Site 1, Rathmichael
Hearth site with associated postholes 32290 22186
Just downslope from Site 2 in Rathmichael a hearth and a number of possible postholes were identified alongside a French drain.

An irregularly shaped deposit of charcoal-rich topsoil overlay the hearth, which was up to 0.15m deep and measured c. 2m x 1.3m. A small number of granite boulders marked the area of the hearth itself. The natural clay in this area indicated that intense burning had taken place. This area of burning, as delineated by the stones, measured 0.8m x 0.4m. The postholes did not form to any particular pattern, and only one was deep (0.23m).

Excavation yielded no obvious indications of the date of the site.

Site 2, Rathmichael
Fulacht fiadh 32291 22177
This site was uncovered upslope and some 50m south of Site 1, Rathmichael. It was initially identified as a spread of burnt stone (mostly granite) and charcoal across an area measuring 4m x 3m, which extended beyond the limits of the pipeline corridor. This was at most 0.25m deep except where it overlay a rectangular pit.

The pit was just over 1.9m long, 0.8m wide and 0.6m deep. A number of stones had been set around the upper edge as a form of kerbing. This mostly survived on the eastern side. There were no other features associated with this site, although a later French drain lay 10m to the south.

Site 1, Shankill
Probable fulacht fiadh 32345 22006
This site was noted as a spread of burnt material extending from the western limits of the pipe corridor. This spread of burnt stone (shale and granite) and charcoal extended for at least 6m east, into the pipeline corridor, and was at least 9m long (north-south). It was up to 0.4m deep. The natural subsoil below the site was irregular and appeared to have been altered in the past. There was no indication of any other features associated with this spread of material. A second spread of burnt material (Site 2) was present 10m to the north of the site.

Site 2, Shankill
Fulacht fiadh 32345 22006
There was one apparent phase of activity on this site. During this a spread of burnt stone (shale and granite) and charcoal accumulated, part of which was present within the pipe corridor. It extended for at least 7m east, into the pipeline corridor, and was at least 8m long (north-south). This deposit was up to 0.4m deep. The natural subsoil below the site was irregular and appeared to have been altered in the past. There was a rectangular trough associated with this spread of material, lying down the slope to the east. A second spread of material (Shankill, Site 1, above) was present 10m to the south of the site.

The trough had been truncated by a field drain but originally measured c. 1.8m x 1.3m and was 0.5m deep. Two postholes were identified in the surviving corners, suggesting that there had originally been a wooden lining that was deliberately removed in the past or had since rotted away.

Site 3, Shankill
Fulacht fiadh, wedge tomb 32399 22061
There were four phases of activity on site. The earliest probably saw the construction of a subrectangular hut, a cobbled area and a trough. Both the by-products from the firing of the trough and a layer of clay sealed these. The layer of clay that sealed the Phase 1 activity also formed the main construction element of the mound of the wedge tomb, built in Phase 2 of the use of the site. This was in turn buried by the debris from the firing of a second trough in Phase 3. This later trough lay just to the south of the earlier one. The final phase saw the insertion of field drains and the digging of a boundary ditch in the early modern period.

Phase 1, Fulacht fiadh
Phase 1 was marked by an oval (1.5m x 1.1m x 0.3m deep) trough sealed by a deposit of clay (F14) that also sealed a number of deposits of burnt stone and charcoal, a cobbled area (F18) and a line of stake-holes.

A subrectangular hut site, identified at the northern limits of the cobbled area, also appears to be contemporary with it. This suggests that this phase saw the use of a trough alongside a cobbled area and hut site. The stake-holes began parallel to the trough and may have acted as some form of windbreak or screen at the southern end of the cobbled area, shielding the site from the prevailing winds.

The trough had been excavated down to the local shale bedrock and appeared to fill freely with water, which percolated through the beds of shale. A sticky, grey clay, heavily stained with charcoal, filled the trough.

The area of stake-holes measured 3.6m (north- south) by 2.1m and was defined by an oval setting of stake-holes. There was no indication of the presence of an entrance, other than an ill-defined gap in the south-eastern corner. The presence of multiple lines of stake-holes in some places suggested that there were a number of phases of reuse of the site for some form of light hut or tent structure.

The cobbled area measured roughly 4.2m (north-south) by 2.4m and lay between the hut and the line of stake-holes. The cobbles were mainly pebbles and boulders of local shale, with some quartz and granite. A single large granite boulder sat at the middle of the eastern side of the cobbled area. A metal disc (20mm diameter) and a flint flake were found among the cobbles. The metal disc appears to be a coin, possibly of early date, and is likely to be intrusive.

The deposit of burnt stone and charcoal that overlay F18 measured 8m (north-south) by 3m and was up to 0.4m deep. This too had been sealed by F14 and was present below the gallery of the Phase 2 wedge tomb.

Phase 2, wedge tomb
Some time after the Phase 1 use of the site a megalithic structure was constructed incorporating a gallery into a mound, which covered the Phase 1 trough, the stake-holes, part of F18 and F16. The mound was a continuous deposit of silty clay, into which the orthostats of the gallery had been set. Its maximum identified dimensions were 14m (north- south) by 9m. In the area south of the gallery F14 had been heavily stained with charcoal, while north of the gallery it was mid-brown. The mounded deposit of F16 had been sealed with the mid-brown clay (F14) to the north-east of the gallery.

Within the gallery a number of stones and the remains of the cairn had sealed the floor layer, which was a continuation of F14, containing a single irregular lens of charcoal. There was no indication of burials or artefacts. Within the gallery F14 sealed a thin remaining spread of F16.

The floor level of the gallery (F14) contained a small number of granite boulders, up to 0.4m long, although their significance could not be determined.

The ground level had been lowered at the rear of the gallery, suggesting that a pit had been excavated into which the back end of the gallery was inserted. This commenced level with the junction between the first and second easternmost orthostats on the opposing walls of the gallery. The back end incorporated the western closing slab. It is possible that the source of some of F14 was the material that had been excavated from the subsoil to enable the insertion of the tomb.

The main components of the megalithic structure are a gallery of roughly parallel side-walls, orientated on an east-west axis, and a closely set outer walling. The stones are set within an irregular mound (of F14) rather than sockets. Two buttress stones are present towards the eastern end of the gallery, where they rest against the outer walling. Neither could be definitely claimed to be functional. The gallery and the mound material around the orthostats were not excavated, leaving these features in their original position.

There was a gap in the mound at the eastern end of the gallery, identifying this end as the front of the structure. The western end of the gallery is sealed by a low orthostat, and the whole structure had been placed within an artificial depression. This had been excavated into sloping ground. The orthostats in the northern wall of the gallery were noticeably higher than those in the southern wall. Traces of a cairn were present around and within the western end of the gallery. There were no surviving traces of a capstone.

Externally the gallery is some 2.35m long and measures 3.4m across at the eastern end and 1.5m across at the western end. Internally it is 1.95m long, tapering from 1.42m across at the eastern end to 0.96m across at the western end.

The mound surrounding the gallery was not fully examined as the eastern end lay beyond the limits of the site, where it is likely to have been heavily disturbed by a field boundary ditch. Its maximum identifiable width was 14m, and it was at least 9m long. The gap in the eastern end of the mound was 2.14m wide and was at least 1.65m long. It was positioned directly in front of the opening at the eastern end of the gallery. The east-facing entrance is similar to those at nearby wedge tombs at Carrickgolligan and Laughanstown.

Phase 3, Fulacht fiadh
The final prehistoric phase on the site saw the construction of a second trough, just south of that of Phase 1. There was also a 23m (north-south) by 12m spread of charcoal and burnt stone associated with the use of this trough. This spread of burnt material also sealed the gallery of the wedge tomb to a depth of 0.7m.

The trough was c. 1.9m in diameter, and the southern half of the edge had a kerbing of granite boulders. This trough was unlined, c. 0.3m deep and had been cut into a natural spring, which could still refill the trough within 30 minutes of its being completely emptied.

Phase 4, 18th- and 19th-century agricultural improvements
During the last two centuries a boundary ditch and field drains were added to the eastern end of the site. During or before this period ploughing across the site also disturbed the upper levels of the archaeological deposits and scored orthostats of the wedge tomb.

2 Killiney View, Albert Road Lower, Glenageary, Co. Dublin