The mystery of Scotland’s Dùn Deardail hillfort

Standing on a rocky knoll on Sgorr Chalum, Dùn Deardail is an Iron Age hillfort above the River Nevis in Glen Nevis. Located at a height of 1,127 ft (347m) Dùn Deardail is overlooked by the mountain of Ben Nevis (Scottish Gaelic: Beinn Nibheis) and is thought to have been constructed by the Celts in the first millennium BC (1000 BC to 1BC). The fort is associated with Deirdrê of the Sorrows, the tragic heroine in Irish pre-Christian legend, whose story is told in the ancient Irish mythology of the Ulster Cycle. Deirdrê and the three sons of Usnach were said to have lived near the fort for some of the time they stayed in Scotland. 

Dùn Deardail is one of a number of vitrified forts in Scotland. This is when the walls of the structure have been subjected to such intense heat that some of the stones have fused together.  Vitrification has been the subject of much debate and it remains unclear why or how the walls were subjected to this process. It is known, however, that it requires very high temperatures, of around 1,000 degrees Celsius, that have to be sustained for long periods. So fires would have to be built and maintained for a number of days. Dùn Deardail has baffled those who find it difficult to explain how vitrification could work on the scale needed for this fort. It would require large amounts of fuel that would have had to be transported to the remote hilltop in the days of prehistory. The reason for doing it is also a mystery; perhaps when the fort was under prolonged attack; a possible structural component; or vitrification undertaken as a status symbol. Science fiction writer Arthur C Clarke was at a loss to explain the phenomenon and said in 2004: “The oddest thing is these vitrified forts in Scotland. I just thought, how? After all, lasers were not common in the Stone Age."

The first time an archaeological excavation took place at Dùn Deardail was in 2015. That revealed evidence pointing to metal working and the storage of agricultural surplus making it a site of high status. Now archaeologists are returning to this ancient Iron Age hillfort for the third time searching again for clues about the mystery of its construction along with other sites that underwent the same process of vitrification. The team comprise of Nevis Landscape Partnership (Com-pairteachas Tire Nibheis), AOC Archaeology and Forestry Commission Scotland (Coimisean na Coilltearachd Alba). They are also inviting people to attend the Archaeology Festival on Saturday 19th August at the: Braveheart Car Park, Glen Nevis, Fort William from 11:00 to 16:00. Events include a Pictish Warrior School, ancient storytelling, science experiments, Iron Age demonstrations, and the Art-Chaeology Competition with local artists Ali Berardelli & Jen Deschenes. There is also a trip to Dùn Deardail to visit the excavations.


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