Dun Briste (Gaelic for Broken Fort) is an incredible, 45 metres (150 feet) tall sea stack in Ireland.
Dun Briste and the surrounding cliffs were formed around 350 million years ago, when sea temperatures were much higher and the coastline at a greater distance away. Dun Briste was once part of the mailand. There was an arch leading to the rock, but it is believed to have collapsed during very rough sea conditions in 1393. This is remarkably recent in geological terms.
