Slieve Gullion dates from the explosive, volcanic Paleogene era.

Geologists have attempted to visualise what it may have been like by observing the dimensions of volcanoes in Iceland, and drawing conclusions on its size and power based on the comparisons.

What remains as Slieve Gullion today is really only the lower levels of the original volcano after much of it disappeared due to erosion.

Geologists from all over the world have been here to study the site, and in particular the distinctive Ring of Gullion.