2005:410 - COOLDRINAGH, Dublin

Testing was conducted at the site of a proposed extension to the water treatment plant at Cooldrinagh, Leixlip, Co. Dublin. The proposed development site was located in the northern part of the site of a former golf course. Previous work in the general area had shown evidence of Early Mesolithic activity at a number of locations, as well as archaeological features and artefacts of early medieval date. The site lies in the bow of the River Liffey which borders Cooldrinagh on its west and northern sides. The original riverbank in the vicinity of Cooldrinagh was submerged during the creation of a dam in the 1950s, as were the set of rapids known as the ‘Salmon Leap’, which originally lay some 400–500m upstream. A Mesolithic core axe was found several years ago in a garden in the townland to the immediate north of Cooldrinagh, which is also the townland in which the Salmon Leap was located. The Cooldrinagh landscape is dominated by two large ridges located at its northern end; the more prominent of these ridges is orientated east–west, with its western end situated close to the river edge, and the other, a short distance to the east of the former, is orientated north–south. While deceptive at first glance, all of the higher land at Cooldrinagh is approximately the same height above sea level and its undulating topography results from the action of post-glacial meltwater, which eroded a series of river channels through the land.

Because of the known sensitivity of the area with respect to the Early Mesolithic period, a ploughsoil walkover survey was carried out in addition to conventional hand-dug test-trenching. The plough­soil survey necessitated the ploughing of the land some months in advance of the planned work to permit weathering of the turned topsoil. The test-trenches were designed with reference to a number of vague anomalies which had been revealed during a geophysical survey, while the two large ridges also received particular focus in the test-trenching plan.

The results of the assessment have further confirmed Cooldrinagh as a significant area with respect to the very early prehistoric period (lithics analysis by Professor Peter Woodman). Combined ploughsoil survey and test-trenching produced an assemblage of 330 knapped flint pieces, distributed across the site in a non-random pattern. A significant proportion of these have been identified as Early Mesolithic. The quantity of lithics identified during the ploughsoil survey was considerably outweighed by that retrieved from test-trenching, although test-trenching covered a relatively small surface area in comparison to ploughed area. Although the ploughsoil survey was designed merely as an indication of flint distribution, part of this discrepancy in quantity may be attributable to the ineffective break-up of the ploughsoil, which was in turn caused by the depth and density of sod cover. The lithics analysis identified concentrations within the lower ground on the east of the eastern ridge and on the flat summit of the western ridge as Early Mesolithic sites and in addition identified other concentrations as locations of possible Early Mesolithic activity. The identification of an Early Mesolithic site on the summit of the western ridge is especially interesting given the apparent relationship between high riverside ground and Early Mesolithic settlement. A significant Bronze Age component was also identified within the lithic assemblage and a number of Neolithic pieces were also present.

In addition, a large cairn was discovered on the eastern side of the east–west ridge. This cairn had been buried beneath a layer of modern material that appears to have been deposited in very recent times, possibly during the construction of the golf course in the early 1990s. This modern material covered the cairn to a depth of almost 1m in places but appeared to have done minimal damage to the actual structure of the cairn. The cairn was constructed of angular stones within a soil matrix and appeared to reach a maximum depth of c. 1m in its centre. Additional trenches were opened along the line of the periphery of the cairn and a number of possible kerbstones were also revealed. A conspicuous amount of burned bone was evident in the soil to the immediate west of the cairn and occasional fragments were also found within the actual fabric of the cairn itself. Included amongst this bone were a number of very worn human teeth. The location of a burial cairn in such a prominent visual setting is not surprising, while the location of the ridge at Cooldrinagh within a bend of the river may also have some significance in this respect.

What is tentatively identified as a polished stone ball, a typical passage tomb find, was found in the ploughsoil at another location within the proposed development area, although at some distance from the hilltop cairn.

In addition to the cairn and the flint concentration, further evidence of activity in the form of a number of linear features, some of which may represent drainage channels, was identified on the western side of the western ridge. The only dating evidence which came from this cluster of features consisted of a sherd of modern ceramic and an iron nail from the stratigraphically latest of the group.

Further evidence of early settlement associated activity was identified within another test-trench. This consisted of a number of cultivation ridges of uncertain date, two possible post-holes, some pits and a definite area of burning that also produced two fragments of worked flint. This area of burning also produced charcoal that gave a radiocarbon date of mid-fourth millennium BC. Charcoal from one of the pits produced two radiocarbon dates of early second millennium BC. These dates accord well with both the Bronze Age component within the lithics assemblage and with the probable date of the cairn.

A possible archaeological feature was also identified at the eastern end of another trench. This consisted of a depression, containing three different fills, within the surface of the natural. However, given that the edges of this potential feature extended beyond the limits of the test-trench, the exact configuration of it was not defined and it is impossible to know whether it represents a cut feature or a mere undulation on the surface of the subsoil. The fills produced one blade fragment identified as of possible Early Mesolithic date and two flint flakes.

A series of five or six stake-holes were identified in Test-Trench 4. These formed an arc which appeared to extend beneath the baulk on the southern side. Some of these stake-holes were inserted into the ground at an angle consistent with a circular structure with its centre to the south. A charcoal sample from one of these stake-holes produced a date of 16th–18th century AD.

Most of the curvilinear anomalies identified during the geophysics survey proved to be the result of water pipes and electricity cables running through the site, although a linear area of high magnetic resistance was revealed to be a possible gravel trackway. This feature was associated with modern ceramics.

Due to the increasing evidence of the archaeological significance of the proposed development site, plans to build the water treatment plant at this precise location were withdrawn.

31 Millford, Athgarvan, Co. Kildare