2008:477 - Maynetown/Portmarnock, Dublin

A small excavation was carried out at the site of two monuments located in the townlands of Portmarnock and Maynetown, Co. Dublin. The sites, which are both to be preserved in situ as open grassy areas within a large-scale residential scheme, included an oblong-shaped mound (Portmarnock DU015–014) and a ploughed-out circular enclosure (Maynetown DU015–055).
As no upstanding remains of the Maynetown enclosure survive, it was subjected to a detailed geophysical survey in advance of the excavation. This revealed the presence of a large circular enclosure, c. 70m in diameter, that contained an unusual ‘avenue’ feature, defined by two parallel ditches leading away from an east-facing entrance. After studying the geophysical survey results it was decided to excavate a section across the enclosure ditch and also across one of the avenue ditches. The section opened across the enclosure ditch revealed that it was a substantial cut measuring c. 7m wide by 2m deep. It had a broadly concave profile and was filled by a number of silty clay deposits that contained much charcoal, butchered animal bone and sea shell (oyster, mussel, razor shell, periwinkle, cockles etc.). The lower fills were waterlogged in nature and contained lenses of organic material including decayed wood and grass. A ferrous nail/pin was recovered from the final fill, while a charcoal sample from the primary fill was dated to ad 687–887 (2 Sigma). A section was also excavated through the southern avenue ditch and this revealed a cut measuring c. 5m wide by 1.2m deep. It had a concave profile and was filled by silty/sandy clay deposits that contained occasional seashell, butchered animal bone and charcoal. After the excavation was completed both of the trenches opened were covered in terram and backfilled.
The mound at Portmarnock is oblong in plan and measures c. 27m north–south by 14m by at least 3m in height. However, originally the monument may have been considerably larger as it was severely damaged in the early 1970s when an attempt was made to level it during field clearance works (local landowner, pers. comm.). The mound is currently covered in low scrub and a small thorn three is growing out of its southern side. As part of this excavation programme the mound was initially stripped of vegetation and then a detailed topographical survey was carried out which allowed for a scaled, three-dimensional plan to be created. Two test-trenches were then hand-excavated into the eastern side of the mound. Due to health and safety considerations the trenches were stepped and the very centre of the mound was not reached. The trenches revealed that the monument was severely disturbed by modern activity, but despite this truncation some intact mound deposits were identified. These consisted of relatively sterile deposits of dumped clay that contained infrequent pieces of shell and charcoal as well as occasional sherds of medieval pottery, suggesting that the mound may in fact be medieval in date. If this is the case then the mound may associated with a medieval village which was identified by Colm Moriarty 45m to the north-east (see No. 485 below, 08E0376).
Post-excavation work for these two sites is ongoing.