The Giant’s Causeway in County Antrim was formed much faster than scientists previously believed, according to new research. Volcanic activity that created the iconic basalt columns took place over just 5.5 million years, about eight million years less than earlier estimates.

The findings come from a study by the Geological Survey of Northern Ireland and the British Geological Survey. By reconstructing a high-resolution timeline of volcanic rocks across Northern Ireland, researchers were able to compress the timescale of the formation process.

The Causeway’s 40,000 basalt columns were formed when molten rock forced its way through cracks in the earth, then cooled, contracted and cracked into the distinctive shapes seen today.

Dr Simon Tapster, a geochronologist at the BGS, said the team pieced together a tapestry of volcanic rocks across the North Atlantic, focusing on Northern Ireland, to reassess a globally significant volcanic event. That event, which occurred about 60 million years ago, can now be linked to formations as far away as Greenland.

The new timeline also connects the Giant’s Causeway more definitively to other landmarks, including Fingal’s Cave on Staffa in Scotland, and volcanic features on the Inner Hebridean islands of Mull, Rum and Skye. Within Northern Ireland, the Antrim Plateau’s earliest lava flows and the Mourne Mountains are now understood to be part of the same volcanic episode.

Researchers say the ability to match up these distant sites provides a much more precise global context for the formation of the Giant’s Causeway.