Coastal Erosion and the Promontory Fort: Appearance and Use during Late Iron Age and Early Medieval County Waterford, Ireland

Promontory forts are an understudied but distinctive maritime archaeological feature from the Iron Age to the early medieval period from northern Spain to Scotland. Their coastal location renders them susceptible to erosion and loss to history, a situation exacerbated by increased storm frequency and sea level rise. Reconstruction of their original form is important to determine their role in the society of the time. This paper concentrates on a particularly notable group of promontory forts along the Copper Coast of Co. Waterford, where traces of up to 32 remain today within a 24 km stretch of coastline. The methodology has involved using oral tradition, historical records and field survey. This has been enhanced by aerial survey using drones and light aircraft. This paper models the data to estimate areas eroded and show how forts were once significantly larger and dominated coastal resources with an economy of farming, fishing, mining and trading. This paper calculates a likely erosion rate of 4–5 cm/yr and anticipates the last remains to be lost in 350 years, perhaps sooner with climate change.