2018:148 - Dún Ailinne, Kildare

A four-week excavation was carried out at Dún Ailinne, Co. Kildare, during June and July of 2018 in the context of an archaeological field school. Students and staff came predominantly from George Washington University, New York University, and the Blackfriary Archaeology Field School. The goal was to explore two features identified through a geophysical survey (2006-2008) as being of archaeological interest for understanding the Iron Age use of the site. These two features are circular and intersect each other, the one to the north slightly larger than the one to the south (18m diameter versus 14m diameter respectively). They are located within a large enclosure that rings the summit of the hill (identified through magnetometer survey and explored through excavation in 2016) but are about 50m to the north-north-west of the Iron Age timber structures identified in excavations from the 1960s and 1970s.

To explore these features we excavated twelve contiguous 2m x 2m units arranged across the north-west arc of the northern feature and extending about halfway across the top of the southern feature. Although the excavation was limited in extent and therefore preliminary, we were able to determine that the two features were similar in a number of ways. Both were relatively narrow, shallow ditches (typically less than 0.5m wide and 0.2-0.4m deep) which contained dark, silty, rocky sediments and were cut into bedrock in places where the bedrock was relatively shallow. Neither feature produced a significant number of artifacts. Only twelve flakes (flint and chert, most small) were recovered, three from the features and the rest mostly from the plough soil. A sample of lightweight material, probably slag, was also recovered from the northern enclosure. Its origin is uncertain but its weight suggests it is not from metalworking, and it may be related to glass working instead. Both features also contained scattered concentrations of charcoal and burned (calcined) bone throughout their fills.
Several dozen bone fragments were recovered, none more than 10mm in length, and they could only be identified as coming from mammals. None were sufficiently numerous in any one place to be considered a true deposit (such as a cremation) but they did tend to occur with charcoal, some fragments of which were considerably larger. Thus it is unknown whether they represent now-scattered funerary remains or were the result of the accidental incorporation of faunal material into the ditch fills (or even both).

The primary difference between the two features is that the northern one has two ditches, at least in the area excavated. These are 0.65-0.75m apart and are presumably concentric, though it is unclear what happens to the second ditch in the southern part of the enclosure (based on the magnetometer image). There was no clear evidence of a bank between the two ditches, but the rock in the fill may have originated from such a bank. These ditches were also discontinuous, though the location of the gaps suggests this is a result of disturbance rather than being a deliberate entrance. The southern feature is composed of a single ditch. While we excavated a shorter section of this ditch, so far it appears to be continuous. A relatively large fragment of burned wood (about 100mm long and 50mm in diameter), which retained preserved bark in places, was recovered from the ditch fill of this feature; it has been identified as hazel. This sample has been submitted for radiocarbon dating.

While there are several possibilities for the specific function of these two circular features, their characteristics as they are currently known suggest they are both ring ditches, the northern one double and the southern one single. While double ring ditches are unusual in Ireland, they are not unknown. The date of this one has not yet been established, but if it is associated with the Iron Age activity at Dún Ailinne, it would not be surprising that it was more elaborate than is typical, given the importance of the site in this period.

In addition to these two circular features, we also encountered a number of possible stake-holes (up to six), a post-hole, one probable pit, and several other features of uncertain function. All material, including the lithics and samples of charcoal and calcined bone, were deposited at the National Museum.

Anthropology Department, GWU, 2110 G St, Washington, DC 20052, USA