- Dún Aonghasa
The ground plan or architecture of an individual stone fort may give clues as to its date. In the case of Dún Aonghasa however theories as to its date varied widely. A programme of archaeological excavation was therefore carried out at the fort between 1992 and 1995. Initially, because of the thin soil cover on the hilltop, it was thought that very little archaeological evidence would have been preserved within the fort. This was not the case however and the excavation proved exciting and informative
Dún Aonghasa is the largest of the stone forts being studied by the project - placed end to end the enclosing walls would stretch for over a mile. The fort stands at the cliff edge (87m or 285 feet high at this point) on the southern coast of Inis Mór and on a clear day it is possible to look down the west coast of Ireland as far as Mount Brandon - some 120km distant. It is a spectacular location and from within the fort the occupiers could have monitored any sea traffic approaching from the mainland - either from Connemara to the north or from the Burren to the east.
There are three main enclosing walls dividing the fort into an inner, middle and outer enclosure; a fourth wall gave added protection along the West Side. The walls were built of drystone rubble quarried on the hilltop. The large scale quarrying carried out has altered the hilltop considerably - the middle and inner enclosures now consist of relatively level ground but originally this area would have been stepped or sloped and probably covered in stony scree. Quarrying of the bedrock around the inner enclosure has created an elevated rock plateau that gives the inner enclosure a citadel like appearance.
The chevaux de frise, which lies outside the middle enclosure, is the most spectacular example of this feature known to survive in Europe. The individual uprights are up to 1.75m in height and were supported by rubble or quarried steps in the bedrock. The band of uprights is up to 38m thick in places. Large set stones along the outer edge suggest that the outline plan was first demarcated on the ground - the stones were then quarried on the spot and swivelled into an upright position.
The remains visible at the site today consist of a number of building phases and to a large extent later building now obscures the earliest work. During the excavations it was possible to examine the walls in closer detail and 3 main phases of building were identified. However there was some activity on the hilltop before it was first enclosed at the beginning of the Late Bronze Age (around 1100BC). Radiocarbon dating of food remains found in the inner enclosure date this pre-fort activity to around 1500BC. We do not know if people were living there permanently or even seasonally at that time - they may have been coming to the hilltop to celebrate certain events in the yearly cycle. The three building phases identified represent three key points in the history of the fort when major alterations and rebuilding were carried out - once built however it is likely that the fort was modified and repaired on a continuous basis.
Phase 1: Sometime around 1100 BC the enormous task of enclosing the hilltop commenced - 14 acres in all was enclosed and one can imagine the hilltop as a hive of activity with stone being quarried and carried or shunted with the help of wooden rollers or pulleys. The remains of this early wall can still be seen today along the eastern section of the outer wall (or immediately to the left as you come into the fort from the modern pathway). The wall was built by piling rubble against large upright stones and was faced only on the exterior. Further uphill a more conventional wall, faced on both sides, was constructed.
During the Late Bronze Age (1100 - 500 BC) a substantial hillfort existed on the hilltop. It seems likely that a small group of the ruling elite lived within the hillfort. The remains of houses were found during the excavation but these were too poorly preserved to determine their ground plans. The houses were built of timber with the main timbers resting on stone foundations or pads - today all that survives are the stone foundations.
Food remains were plentiful and included fish, sheep and cattle bones, limpet and periwinkle shells. Some grains of barley and a number of saddle querns for grinding grain were also found. Large pottery vessels (shaped like modern flowerpots) were used for cooking over open fires - food remains in these pots suggest that a pottage was made from grain and wild plants.
Stone was the main raw material used for making tools - axes, hammers, grinding stones, whetstones and pot covers were made. Pumice was collected from the shore and used like modern sandpaper for the fine finishing of bone pins and needles. Decorative items included beads made from bone, stone, pumice, glass and amber. The presence of amber indicates that the inhabitants were wealthy as they had to trade for this exotic material - most of the amber that was circulating in Ireland during this time came from the Baltic.
The most interesting group of finds from the excavation was a collection of clay moulds which had been used to cast bronze objects. The objects cast included a sword, spearhead, knives, socketed axeheads, rings or possibly bracelets and a number of different types of pin used for fastening clothing. We do not know if these objects were for use by the elite of the tribe or whether a special hoard of goods was being manufactured as an offering to the gods. Four perforated bronze rings were found together near the cliff edge inside the fort. It seems likely that these were deliberately buried - Late Bronze Age votive hoards were very often deposited in watery places and the rings may therefore represent such an offering.
The remains of a large fire within the inner enclosure may have been a feasting area. Cattle and fish bones were scattered around the edge of the fire and the only remains of pig at the site also came from this area. In Early Historic times (around 500 AD) pig meat was associated with feasting in Ireland and this may have been a continuation of a far older tradition. Pigs were probably rare on the Aran Islands however - though there was undoubtedly some tree cover in the more sheltered spots it seems unlikely that there was sufficient oak forest to provide mast for foraging herds of pigs.
Phase 2: We do not know when the Late Bronze Age hillfort was abandoned but a series of radiocarbon dates indicates that there was a fall off in activity at the fort after 500 BC. Thereafter the details of the history of the fort become more obscure - it may be that the fort was no longer intensively or extensively occupied after that time. The Phase 2 building alterations may have been prompted by the same events which resulted in the construction of a large number of coastal promontory forts along the west coast of Ireland. During this phase it seems likely that the triple wall defences were built along the western side of the fort and the chevaux de frise was also erected. Very little archaeological remains can be associated with this phase - the remains of a structure and pits in the middle enclosure could conceivably have been a small Iron Age temple.
Phase 3: This final phase is also undated but by comparison with other forts such as Dún Eoghanachta or Cahercommaun in the Burren, the final remodelling of Dún Aonghasa may have taken place sometime in the period 500 - 900 AD. At this time the inner wall was probably substantially thickened and heightened giving it its present day appearance. There was some trace of occupation contemporary with this phase of building but it appears that during this time the fort was not a major settlement. It may have had other functions however - like Grianán Aileach it may have been a royal seat used at particular times for the carrying out of inauguration rites or administrative or judicial functions. It also no doubt represented the territorial dominance of a ruling dynasty. The presence of six other large forts on the islands at this time may mean that the monopoly of power enjoyed by the Late Bronze occupants of Dún Aonghasa had fragmented but it is also possible that those who controlled the forts in the Early Medieval period were members of a single powerful dynastic group.