2004:0509 - DUBLIN: 24–26 Ardee Street, Dublin

The excavation of this 1.5ha site, reported in Excavations 2003 (No. 494), continued until February 2004. The site occupies the corner of Ardee Street and Cork Street and is bounded to the west by Robinson's Court and to the north by a large masonry-and-brick wall which was constructed c. 1680.

The most substantial feature recorded over the site was a large homogenous deposit of grey clay silt, present on all areas of the site but at its most substantial in the centre, where it was at least 2.75m in depth. The deposit rested in a depression in the natural subsoil, which may have had a formal cut edge on the northern side but sloped gradually down elsewhere. This has been interpreted as being the silted-up remains of a millpond associated with the nearby abbey of St Thomas.

The pond appears to have been fed by the Commons Water, a natural watercourse that has its origins in Drimnagh, formerly the Commons of Crumlin. The stream extended across the centre of the site and was underpinned and covered by a brick arch by Dublin Corporation in 1874. The excavated evidence suggests that the underpinning partly replaced an earlier formal channelling of the stream, which had run along its pre-2004 course at least since 1684. It is possible, however, that the stream originally ran further to the north and its pre-2004 course was constructed sometime after 1603. The Commons Water formed the parliamentary boundary of the City of Dublin in the 19th century. This was a successor to the medieval boundary of the city's liberties and was thus included in the Riding of the Franchises, where the marshy area is documented.

The millpond basin presented as an oval-shaped saucer, oriented south-west/north-east, with a relatively flat bottom. At its most extensive, it measured c. 50m (north-south) and at least 53m along the notional Commons Water axis. There was no evidence recorded along the base (with the possible exception of a small gully) for erosive action indicating the course of the Commons Water through the area. The base of the culverted watercourse was, in any case, well above the base of the millpond. The only real indication that the edge of the millpond may not have been natural was towards the north, where the break in slope was less gradual than elsewhere. This, however, may be a function of the ground rising slightly more sharply at this point.

Environmental samples of the millpond fill were wet-sieved and no identifiable organic remains were revealed. While there was a significant organic content evident in these sieved fractions, it was all finely comminuted. The deposit did not, however, appear (macroscopically) to be humified and there was no impression gained during manipulation of the soil that its structure was supported by organic matter. The deposit therefore appears to represent a single deposition event, probably an event of short duration ('"short" being of a duration less than that required to establish bottom-rooting or overhanging plants, so less than a couple of years', Thomas Cummins, pers. comm.).

Milne found that the build-up of silts at Trig Lane in London could be estimated at c. 10–20mm per annum, although the silts in this case were deposited by the Thames (Milne 1981, 36). At its greatest extent, the millpond deposit was 2.75m in depth, but there was no artefactual evidence recovered to provide a terminus ante quem for the cessation of the sedimentation process. Working (very roughly) on the Trig Lane model and calculating the historical evidence for when the millpond contained water and from when it could be crossed on planks, it should have taken approximately between 140 and 275 years to silt up. Historical sources suggest that a man drowned in the millpond in 1326 and it was possible to cross it on planks by 1527, 200 years later.

The most significant post-medieval find was the remains of a defensive earthwork thrown up by troops loyal to the Duke of Ormond in 1643. The defence of the city increasingly became an issue towards the end of 1642 as the political situation became even more volatile, with several armies and armed factions competing for the countryside. A Confederate force had been defeated in Swords in January; however, over the summer Dublin merchants complained that raiding parties were encroaching to within half a mile of the capital. The same merchants avoided ordering in provisions, to prevent the army confiscating them. It was not until the winter of 1643 that serious attempts were made to fortify the city and these are outlined in a document entitled Military arrangements at Dublin.

The defences were depicted on the Down Survey map of 1655–1656; it is, however, important to note that there were several phases of defensive works undertaken between 1643 and 1650 and the map depicts the cumulative effect of all of these works. The evidence from Ardee Street presents as an earthen bank located over the medieval Abbey Stream, but in front of the stream's main channel. It is additionally likely that the millpond, which was silted up in 1603, could have been deliberately flooded, forming an additional defensive feature to the west of the bank flanking the approach to the city along Cork Street.

The earthen bank survived over a distance of 5.8m (north-south), its truncated top just 2m to the west of the eastern edge of excavation. It survived to a height of 1.14m, which was just 0.6m below the level of the pavement outside the site. It was probably therefore much higher, although it is difficult to estimate exactly how much so. The bank was recorded in a much more truncated state further to the north of the excavated area.

The bulk of the material comprised silty clays which ranged in colour from yellow through to dark-brown. The clays were sterile, although there was occasional evidence for crushed molluscs, which would suggest that, as unlikely as it appears, the bank was composed of redeposited millpond material. No tip lines were evident, but this is possibly a function of the dense homogeneous nature of the material used.

Sealing the bank material was a deposition of hard yellow stony clay which also contained a grey sand in its matrix. It is possible that this material represents a capping of the bank with redeposited subsoil, as opposed to millpond material. Subsoil would obviously have constituted a more stable bank material, but it is possible that the bank may have been revetted and that the evidence for this work was removed by scarping that took place prior to the construction of the brewery to the west. The bank was truncated to the north by the insertion of the brick cistern associated with an 18th-century brewery, the foundations of which respected the slope of the underlying material.

A large square pit cut through the bank material. It measured 1.5–1.74m across and was some 0.66–0.93m deep, with vertical sides and an irregular base. The primary fill was a greenish-blackish-grey, sticky, strongly smelling organic clay-silt up to 0.25m in depth containing fragments of leather shoes. This cess-like material was piled up in the centre of the pit, away from the edges. This fill contained clay-pipe fragments dating to the period 1640–1680. A sample of the fill was retained for environmental analysis.

The pit may have been a makeshift latrine, but there was no evidence recorded for an associated temporary structure. While it is highly likely that the troops guarding the defences would have had a formalised latrine system in operation, it is odd that a latrine would have been situated at such a visible location. An examination of the environmental remains may throw further light on the pit's function.

The defensive bank may survive at other locations around the city and excavators working along its extent should be aware of its existence.

Reference
Milne, G. 1981 'Medieval riverfront reclamation in London'. In G. Milne and B. Hobley (eds), Waterfront archaeology in Britain and Northern Europe, CBA Research report 41, 32–6. London.

27 Merrion Square, Dublin 2