2007:552 - THORNTOWN, Dublin

A programme of testing was undertaken on behalf of the Irish Prison Service for the proposed new prison facility at Thornton Hall, in the townland of Thorntown, North County Dublin. The proposed development site consists of Thornton Hall itself and its associated 150 acres of farmland. The townland boundary of Thorntown and Kilsallaghan defines the eastern edge of the site, while R-class roads (R130 on the west side) and modern dwellings define the remaining boundaries.

A number of non-intrusive surveys of the proposed project area were requested in order to assess the lands for sites of archaeological, architectural, historical or cultural heritage value. These surveys included a desktop study, a field inspection and a geophysical survey. Only the geophysical survey produced information of archaeological interest. In addition to a number of small geophysical anomalies throughout the project area, several large features were detected by magnetometer survey. These consisted of three enclosures, a possible enclosure, a possible ring-ditch, a likely modern curved anomaly and the remains of a laneway that had been evident on earlier edition OS maps.

Testing of the site was conducted over a period of twenty weeks from 5 December 2005 to 28 April 2006. Eight of the sites identified during the earlier geophysical survey were tested. In addition, one hundred 10m by 10m boxes were randomly set throughout the project area and excavated, while all ground investigation and landscaping works were monitored.

Site 1 consisted of a large subrectangular enclosure situated on a natural ridge, with possible ancillary enclosures (perhaps animal corrals), which was serviced by drainage ditches running down either slope of the ridge. Radiocarbon dates from the main enclosure ditch and from two ancillary ditches indicate a mid- to late 7th-century date for this site. The find of a lignite bracelet fragment within the ditch fill would seem to corroborate these dates.

Various linear features identified in Site 2 appeared to be agricultural in origin (drains, plough furrows and lazy-beds), of both post-medieval and yet unknown date.

Trench 1 of Site 3 was located downslope of the enclosure at Site 1 and revealed what appeared to be part of a drainage system, possibly serving the Site 1 enclosure. An early medieval date for these features may be corroborated by the recovery of pottery in the later deposits in this trench. Trench 2 revealed a pit and a series of linear features with evidence for metalworking in the form of slag within their fills. A radiocarbon date from the pit indicated a 9th-century infill date.

Site 4 consisted of a large plectrum-shaped enclosure. Radiocarbon dates recovered from the ditches of the enclosure suggest a late 8th- to early 11th-century date for this site. This was possibly therefore an occupation site of early medieval date, though of a later date than the subrectangular enclosure at Site 1 to the north.

Site 5 consisted of a circular-shaped enclosure formed from two ditches, with entrances at its east and west sides. The area enclosed measured c. 30m in diameter. One possible pit was identified within this enclosure towards the north side, while a group of possible pits were identified c. 11m to the south of the enclosure. An irregular-shaped linear anomaly was also identified running along the west side of the enclosure at a distance of 2–6m. This anomaly was broadly aligned from north to south but turned to the south-east towards its terminus, in the direction of the possible pit south of the enclosure. Radiocarbon dates recovered from the southern ditch of the circular enclosure produced a date range of 2880–2580 BC, while those recovered from the burnt area to its south have produced a date range of 2470–2220 BC. These dates place both the enclosure and the burnt area in the Late Neolithic to Early Bronze Age transitional period. Cord-impressed pottery and a stone axehead recovered from this burnt area support these dates. It would appear that the enclosure may be the remains of a ploughed-out ring-barrow; the burnt area to the south of the enclosure was tentatively identified as a cremation pyre and a possible cremation pit was identified in the interior; however, burnt bone recovered from its fills was identified as non-human (Laureen Buckley, pers. comm.). It is possible that cremation burials were inserted into the mound itself; if so, any such cremations would have been removed along with the mound material.

A large L-shaped ditch was identified in Site 6, apparently the south-east corner of a large rectangular enclosure. Pottery recovered from the ditch fills was medieval, of probable 12th–14th-century date; these finds, together with the morphology of the enclosure ditch and the geophysical testing results, would support the interpretation of the L-shaped ditch as representing the remains of a moated site of Anglo-Norman date.

Testing revealed that geophysical anomalies identified in Sites 7 and 8 are of late post-medieval date and contained water pipes along their bases, suggesting an agricultural function. Archaeological investigations of Site 8 also uncovered an informal dirt track marked as ‘quarry road’ on early maps.

Of the one hundred 10m by 10m random boxes excavated, eighteen contained archaeological material of varying date. No archaeology was identified from any of the landscaping or engineering monitoring works undertaken at the site.

Editor’s note: For a variety of reasons, this summary was unavailable for publication in the bulletin of 2006.

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