Volcanic activity, not legend, formed Giant’s Causeway, scientists find

This volcanic event is now understood to be globally significant, with evidence found in rocks as far away as Greenland. For the first time, researchers have definitively linked the initial lava flows on the Northern Irish plateau to the same volcanic activity that formed similar basalt columns in Fingal's Cave on the Scottish island of Staffa, rocks previously believed to have formed millions of years later. Rock formations in the Mourne mountains, the Hebridean isle of Rùm, and magmatic activity on Skye are also connected to this event, providing a more precise global geological context and timeline for volcanic activity across Northern Ireland.

Dr. Simon Tapster, a geochronologist at the British Geological Survey, stated that by piecing together volcanic rocks across the North Atlantic, particularly in Northern Ireland, they were able to reassess a major globally impacting volcanic event and its shorter duration. While folklore tells of Finn McCool building the causeway to fight his Scottish rival Benandonner, scientific analysis shows the columns formed as thick molten rock rose through the Earth's crust, cooled, contracted, and fractured into mostly hexagonal shapes. This research is part of a broader BGS initiative to enhance understanding of the UK's geology by better quantifying geological time.