2015:148 - Keel East, Mayo

The second season at the Cromlech Tumulus site on Slievemore (MA042-021002) concentrated on Quadrant 3 at the north-west of the site, completing the investigation of the western half of the Cromlech Tumulus.
The trench investigated the interior and north-western part of the wall of a large oval-shaped Middle Bronze Age building which has previously produced a radiocarbon date of 1409 and 1229 BC. The wall of the building was examined in detail and shown to be a complex construction with stone faces retaining an earthen core. The outer wall face consisted of several courses of long narrow boulders whilst the internal wall face consisted of large upright stone slabs on top of which rested several courses of neat dry stone work made out of medium sized stones. The earthen core consisted of thin layers of yellowish brown charcoal-rich soil, suggesting the material had been relocated from elsewhere, possibly a nearby midden deposit. The three elements combined to create a wall 2.4m wide and 0.7m high.
The interior of the building contained a dense spread of features. Around the perimeter of the building there was a band of substantial post-holes, with diameters of around 0.4m and depths of between 0.4m and 0.8m. Although not displaying a particularly regular pattern it did seem that two concentric rings were present, and the close spacing between the two rings suggested they had not been used simultaneously. In the central area there was a dense spread of smaller post-holes, stake-holes and shallow pits. The density of features within the central area again suggests a lengthy and complex period of use for the building, rather than the features all being in use simultaneously.
An unusually large pit was found close to the northern perimeter of the building, where it had cut through a series of earlier post-holes. A very unusual artefact was recovered from the upper fill of this pit, a small carved stone head made out of a small water-rolled pebble with a quartz core. Two small pieces of plain Bronze Age pottery were recovered from two of the smaller internal features, an extremely rare find for Achill which appears to be essentially aceramic until recent times. The rest of the finds assemblage consisted of small lithic flakes and simple cores, hammerstones and rounded pebbles of unknown purpose. This material is very reminiscent of the finds assemblages from the two Middle Bronze Age houses previously excavated by Achill Archaeological Field School on Slievemore, which are located about 2km to the west.
An unexpected discovery during the 2015 season was to find that a substantial pre-bog field wall was connected to the north-west corner of the site, constructed over the outer edge of the oval building's wall. The course of this wall is difficult to follow as it has been damaged by a small stream, but it appears to continue northwards from the site for some distance.
Work is due to continue in this eastern part of this site during 2016.

Achill Archaeological Field School, Dooagh, Achill, Co Mayo