2016:394 - Station Road, Portmarnock, Dublin

Monitoring and subsequent excavation was carried out in response to condition 28 of a permitted housing development at Station Road, Portmarnock, Co Dublin (Planning Ref. F13A/0248). The work was carried out for Sherman Oaks Ltd. The development site is located on the east side of the railway line at Portmarnock and fronting onto the south side of Station Road and is known as Phase 1A. Monitoring at the site followed previous archaeological investigations in the area including the wider lands to the east and south owned by Sherman Oaks Limited. These investigations included geophysical survey (Sheil et al 2000, Nicholls 2002, Leigh 2004), archaeological testing (Wallace 2000, Phelan 2004, Moriarty 2007), archaeological excavation on lands to the north-east of the Phase 1A development adjacent to Station Road (Moriarty, 2008) and monitoring related to the erection of fencing around two previously known monuments which are to be preserved in situ, DU015-014 and DU015-055 (Walsh 2012).

In February 2016, monitoring works were carried out in response to conditions attached to a Tree Felling Licence (FL18908, Item C). The tree felling licence provided for the removal of trees and hedgerows on the Phase 1A site prior to the construction phase of the permitted housing development and these works were monitored.

Monitoring of topsoil stripping for the Phase 1A housing, associated site compound areas and infrastructural works including temporary attenuation ponds and pipelines commenced in March 2016. The bulk of the monitoring took place between March and July 2016 and continued intermittently into early 2017. The last area of topsoil stripping was monitored over two days from 8 May 2017.

In total seven archaeological areas were identified during monitoring, five of which were small-scale features (Areas 1, 2, 3a, 4 & 5) and one was a large sub-square ditched enclosure (Area 6). Following consultation with the National Monuments Section of the Department of Arts, Heritage, Regional, Rural and Gaeltacht Affairs (DAHRRGA) six of these areas were fully excavated and preserved by record. Excavation of Areas 1, 2, 3a and 4 took place from 17 May – 28 June 2016, Area 5 from 25-29 July 2016 and the Area 6 excavation took place from 17 August to 21 October 2016.

Area 5a was identified immediately to the east of a medieval village which was the subject of a previous excavation adjacent to Station Road (Moriarty 08E0376, DU015-031001-006) and is probably an extension of that medieval activity. One of the temporary attenuation ponds serving the Phase 1A development was adjusted to avoid the archaeological site and the remains were covered with terram. The topsoil was reinstated pending resolution of this area in advance of any future development proposals.

Targeted testing was also carried out on a sub-surface enclosure site (DU015-014001) under this licence and this confirmed the nature and extent of the enclosure. This enclosure was subsequently fully excavated under license no. 16E0613.

Area 1 comprised three ditches, two of which were oriented east-west and one oriented north-south identified during monitoring of a 2m-wide pipe trench to serve temporary attenuation pond no. 2. The ditches contained medieval pottery, animal bone and seashells and represent peripheral activity associated with the previously excavated early medieval settlement (Moriarty, 2009). (ITM 723329E 742398N).

Area 2 comprised a pipe trench between temporary attenuation pond no. 2 and Station Road. The area requiring archaeological investigation measured 12m long by 2.2m wide and contained a metalled surface, two linear ditches and a pit feature. (ITM 723343E 742463N). The character of the metalled surface and associated finds suggest a medieval date and C36 may also represent medieval activity. The other features investigated in this trench represent a post-medieval field boundary and drainage ditches.

Area 3a comprised an apparently isolated cereal drying kiln and a linear feature of uncertain function, possibly serving as a windbreak to the kiln, that were identified in a south-west/north-east pipeline trench/haul route from the phase 1A housing development to temporary attenuation pond no. 1. No dateable finds were recovered from these features and it has since been established that these were internal features within ditched enclosure DU015-014001 which was tested under licence 16E0101 and subsequently fully excavated (Area 3, licence No. 16E0613) (ITM 723343E 742312N).

Area 4 comprised the patchy remnants of a metalled trackway that was identified during stripping for Phase 1A housing to the south-east of the Portmarnock railway station car park, to the south of Station Road and comprised an extension of a roughly north-south oriented medieval road/trackway which was discovered during monitoring of topsoil stripping for a temporary car park serving Portmarnock DART Station in 2008. The portion of the trackway exposed at that time was excavated and subsequently allocated SMR no. DU015-137. It was thought likely that monitoring of topsoil stripping for the Phase 1A houses could uncover further remains of this trackway. No trace of the feature was identified to the north of the previous excavation area but patchy remains consistent with a metalled trackway were identified to the south (ITM 723320E 742350N).

Area 5 was located towards the east end of a foul water pipeline to Coast Road, and comprised a large sub-oval or keyhole-shaped pit filled with black soil containing charcoal and burnt stones. Overall the pit measured 5.2m north-west/south-east by 2.4m and it was excavated to a depth of 1.2m. It was not possible to reach the base of the pit in the centre due to water flowing in from below at a fast rate, but it appeared most likely that the base would not have been any more than another 0.1-0.2m in depth. The pit was excavated to 3.48m OD. This pit is most likely to have been associated with a burnt mound of which no further trace was found and it is possible that remnants of a burnt mound could remain outside of the area of the pipeline.

The full extent of the pit was not excavated as it extended north beyond the limit of the trench required for the pipeline (ITM 723657E 742175N).

 

Area 6 comprised a large sub-square ditched enclosure forming a circuit measuring approximately 39m north-south by 50m internally (47m north-south by 56m externally), with an entrance gap 2.5m wide oriented to the north-north-east.  The enclosure was truncated on its western side by a post-medieval field boundary comprising a ditch and bank running from south-south-west to north-north-east. The ditch forming the east side of the enclosure continued south from the south-east corner of the large enclosure for a further 23m in a north-south alignment.  A possible outer enclosure defined by a smaller curvilinear ditch may have enclosed an area to the south of the main enclosure, however during monitoring (before the main enclosure was identified) this ditch did not appear to be of any great significance and just two sections were excavated in that area. The fills were sterile and the cut shallow and no features were evident within this outer area.

 

The enclosure ditch varied greatly in its dimensions over the course of the circuit. The widest and deepest points were the two termini on either side of the entrance gap which were substantially larger than the rest of the ditch cut. The width of the main enclosure ditch ranged from 2-4.75m and the depth ranged from 0.8-2.6m. The ditch cut had a sharp break of slope at the top over most of its course but had a more gradual break of slope to the south-west and in places along its southern arc. The sides were concave and generally steeply sloping with a sharp break of slope to a wide, flat, U-shaped base, except in the vicinity of the entrance.  Here the ditch was broader and more gently sloping on the outer edge before dropping sharply to a narrow, almost V-shaped base.

 

The depth and steepness of the sides of the ditch around the termini in conjunction with the narrow entranceway would have been a considerable obstacle to entry to the enclosure; it was defensive in appearance and must have been even more impressive with an associated bank. The ditch was less impressive elsewhere and perhaps the north-north-east was the most important area from a defensive and visual perspective.

 

It appears that there was originally a gap in the south-east of the enclosure, 4m wide, providing access between the main enclosure and the outer enclosure to the south, which would have allowed movement of people and or livestock between the two areas. At a later date, perhaps when the outer enclosure had gone out of use, the 4m-wide gap was dug out to a depth of 0.5m. This action would have sufficiently impeded access to or from the outer enclosure without requiring the extra effort of excavating this portion of the ditch to the same depth as elsewhere.

 

The enclosure ditch fills contained large quantities of animal bone and frequent seashell and at the lower levels of the deepest parts of the ditch, to either side of the terminals, the fills were waterlogged and contained organic material. Finds from these deposits include a wooden hoop made of yew (Cal AD 686-876, 2 sigma) which was fastened with a leather tie , the end of a wooden cane or staff and a copper alloy pin which appears to be quite an unusual type. It is a baluster-headed example with a spiral ring through the head and a decorated spatula-shaped projection beyond the head. Decoration on the pin and head are in the form of dots and the decoration on the spatula-shaped projection is engraved interlace. The date of the yew hoop corresponds remarkably well with another barrel hoop recovered during testing from a ditch fill in another enclosure 130m to the north-east (DU015-014001) which returned a radiocarbon date of Cal AD 641-763 (2 sigma) (ITM 723039E 742246N, 16E0613).

 

There was no trace of any structures within the enclosure to indicate domestic activity, however there was an inner curvilinear ditch which subdivided the interior. This ditch had an entrance, oriented to the north-north-east, into this space, which mirrored the main entrance to the enclosure indicating that the two ditches are most likely to have been contemporary.

 

Radiocarbon dating results indicate that the main period of use of the enclosure was between the late 7^th - late 9^th Centuries, however the dating and layout of an internal curving ditch suggests continuous occupation from the Iron Age at the site. This ditch had an entrance, oriented to the north-northeast which mirrored the main enclosure entrance. The lower fill of the inner ditch returned a date range of cal BC 347-43 placing this feature in the Iron Age, while the upper fill was dated to cal AD 671-868, indicating that the inner ditch was most likely still in use when the outer ditch was constructed. It implies a continuity of occupation at the site from Iron Age to early medieval period.

 

References:

Leigh, J. 2004 Geophysical Survey Report Portmarnock, Co. Dublin (Licence 04R149). Unpublished report prepared by Margaret Gowen & Co. Ltd for Ballymore Residential Ltd.

 

Moriarty, C. 2009a Final Report Archaeological Excavations at Portmarnock Mound (DU014-015) and the Maynetown enclosure (DU015-055), Co. Dublin (Licence No.: 07E0574). Unpublished report prepared by Margaret Gowen and Co. Ltd for Ballymore Residential Ltd.

 

Moriarty, C. 2009b Final Report Archaeological Excavations at Portmarnock, Co. Dublin (Licence No.: 08E0376). Unpublished report prepared by Margaret Gowen and Co. Ltd for Ballymore Residential Ltd.

 

Nicholls, J. (2002) Geophysical Survey: Baldoyle/Portmarnock Co. Dublin. Margaret Gowen & Co. Ltd. (unpublished).

 

Phelan 2004 Archaeological Assessment and Impact Statement Portmarnock, Co. Dublin (Licence No.: 04E1415). Unpublished report prepared by Margaret Gowen & Co. Ltd for Ballymore Residential Ltd.

 

Shiel, D., Shields, A. and Stephens, C. (2000) Geophysical Survey Report: Baldoyle, Co. Dublin, GSB Prospection (unpublished)

 

Wallace, A. (2000) Archaeological assessment: Portmarnock mound, DU015:014, Portmarnock, Co. Dublin. Margaret Gowen & Co. Ltd. (unpublished).

 

Walsh, F. 2014 Archaeological monitoring at Station Road and Mayne Road, Portmarnock, Co. Dublin, Planning Reference F07A/0947, Licence Ref. 12E358. Unpublished report by IAC Ltd.

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