1986:24 - 'RATHFARNHAM CASTLE', Rathfarnham, Dublin

Excavation was carried out at Rathfarnham Castle from June 24th to August 18th 1986, prior to application for planning permission by Fortlawn Homes Ltd by whom the excavation was funded. The area proposed for development was the northern portion of the castle grounds consisting of approximately 7,500 square metres and standing directly outside the area of the preservation order on the castle.

The purpose of the excavation was to test this area for archaeological remains in view of its close proximity to the castle built by Archbishop Loftus, c. 1585. Facing northwards and at right angles to the castle stands a structure resembling a large medieval undercroft (which now forms the lower storey of the 20th-century extension). This building may pre-date the castle but there is no definite architectural or historical proof of this. No remains of archaeological interest were apparent on the site before the investigation began.

A geophysical survey was initially undertaken at the site. This included infra-red photography (undertaken by Mr Leo Swan) and a magnetometer and resistivity survey (by Dr Martin Monro, Queen's University, Belfast, and Mr Damien MacGarry). On the western side, however, the instrument survey was much impeded by pits, bushes, metal rubbish, etc., and it was decided to extend a series of test trenches across this part of the site, using a mechanical digger.

The excavation on the east side was based on the results of the geophysical survey which had detected two anomalies. The first was a pathway which had been laid, according to map records, between 1778 and 1821. The second anomaly was due to a drop in the level of the ground at which point land-drains were found to have been concentrated.

Excavation revealed a network of drains, the largest of these running N-S for at least 20m. This was a simple ditch-type drain, approximately 3.5m wide and 60cm deep. Most of the other drains, arranged in a haphazard herringbone fashion, ran into it. These consisted of small 'coffin' or 'box' drains, with capstones roughly 30cm in diameter, and ditch drains, up to 2m wide and 1.1m deep.

A considerable amount of late 18th-/early 19th-century pottery was found in the topsoil around and above the drains but was not associated with them. This is significant as a few 17th-/early 18th-century sherds were found within the fill of the drains, suggesting that these structures, which are of types common during the 18th century, may date to no later than the middle of that century. On the W side of the area, a large 'coffin' drain with capstones c. 50cm in diameter had a sand base and extended at least 30m southwards towards a garden wall. The finds from the fill and parallels with other drains of this type indicate that it dates to the late 18th or early 19th century.

In all, over 1,800 finds were recovered, mainly from the topsoil. These consisted mainly of pottery sherds, bottle and window glass, iron fragments and pipe stems of 17th-/19th-century date. It is surprising that of these, only three small pottery sherds belonged to the 16th century or earlier.

Inishquin, Glencullen, Co. Dublin