Case Study: Dun Deardail Iron Age Hillfort

Susan Kruse

The Atlas of Hillforts ( has identified a large number of hillforts in the Highlands, but few have seen modern excavation. The vitrified hillfort of Knockfarrell near Dingwall (MHG7152) was one of the first excavations in Scotland in the late 1700s, where walls of 12 feet high could still be seen. Craig Phadrig in Inverness (MHG3809) has seen work over many years, including recent excavation of a part of the rampart which showed Iron Age but also early medieval and later medieval use (Peteranna and Birch 2018).

Aerial photo of hillfort with trail leading up to it and wall features visible.
Figure 1: An aerial view of Dun Deardail Iron Age hillfort ©FLS by Caledonian Air Surveys

A larger scale excavation was recently undertaken as part of a community excavation at Dun Deardail in Lochaber (MHG4348), providing valuable information on a west coast hillfort. Like Knockfarrell and Craig Phadrig, it was located on a high hill, with remains of fortifications encircling a large area. The results suggest that the hillfort was built in the 5th century BC, and occupation ended sometime in the 4th to 2nd century BC. In the middle of this period, it was burnt in a fire so hot that it melted the rock (vitrification), a fate shared with Knockfarrell, Craig Pharaig and a number of other hillforts in the Highlands.

Figure 2: Vitrified rock at Dun Deardail ©Matt Ritchie

The recent excavations for the Nevis Landscape Partnership were funded by Forestry Commission Scotland and the Heritage Lottery Fund, and undertaken by AOC Archaeology with considerable community participation. They explored the terraced interior of the fort and the nature of the rampart walls. These showed that the rampart was much thicker than thought, and probably topped by a substantial timber structure. As in some other hillforts in Scotland, slots for large horizontal timbers were found within the wall, some even preserving charred timbers. After the fire of c. 310 BC, the fort was reoccupied, with walls refaced and the interior levelled. Despite a tradition that the fort had been reoccupied in the early medieval period, as happened at Craig Phadrig, no evidence was discovered. As a result, the hillfort was probably built, burnt and then abandoned in the Iron Age, in the space of a few centuries.

Clearly considerable resources were needed to build such a large structure, which was defensive but also a status symbol and a prominent symbol of power for miles around. In the interior, hearths show occupation although the nature of any buildings remained obscure. There were few finds recovered, but these included stone tools, metal objects as well as evidence that bronze and ironworking had taken place in the hillfort.

The excavation was also notable for its extensive environmental sampling, both in occupation trenches and from a dated core taken from outside the walls. The waterlogged peat provided good preservation for pollen and charcoal. When published, this will provide valuable information for this area.

The reason for vitrification at hillforts remains a matter of debate, and may have been accidental or deliberate. If deliberate, it is still not entirely clear how fires could have been set and maintained to create the high temperatures needed to melt rock. Science fiction author Arthur C. Clarke maintained this was one of the biggest mysteries he had encountered. Experiments to reproduce vitrification have all failed thus far. The excavations at Dun Deardail have provided further evidence for this ongoing debate.

The excavations at Dun Deardail are important for highlighting aspects of construction at hillforts. It is also significant that dates from the peat core from outside the walls corresponded to the dates in the interior, suggesting possible future strategies for work on hillforts. The project is also a good example of involving local communities and schools. A series of creative events were run in tandem with the excavation. Nevertheless, a number of questions remain, including the hillfort’s place in the landscape, the nature of subsistence and the structures within.

The report of the excavation is still awaited, but a popular booklet has been produced summarising results (Ritchie 2018).

Further information

The Archaeology of Dun Deardail booklet can be downloaded from the Forestry Commission website here.