The Volcano Plug

The term “Volcano Plug” on the Isle of Mull refers to ‘S Airde Beinn, a remarkable geological feature that stands as a testament to the island’s fiery past. Located near the Mishnish Lochs, just west of Tobermory, ‘S Airde Beinn is essentially the worn-down stump of a magmatic conduit, a resistant dolerite core that once fed a much larger volcano around 60 million years ago during the Tertiary geological period. This makes it the largest and best-known example of a Tertiary volcanic plug in western Scotland. Its robust rock has successfully withstood the immense forces of erosion, including the last ice age, leaving behind this prominent and highly significant topographic feature.

Geologically, ‘S Airde Beinn is a Site of Special Scientific Interest (SSSI) due to its unique formation and the presence of rare minerals, such as larnite, rankinite, and wollastonite, which were created as the molten rock baked the surrounding strata. While it’s not an intact volcano in the traditional sense, its summit features a hollow now filled by Lochan ‘S Airde Beinn, often referred to as a “Crater Lake,” which is likely the result of glacial erosion. This makes it a fascinating site for those interested in geology, offering tangible evidence of the intense volcanic activity that shaped Mull into the island we see today.

For visitors, ‘S Airde Beinn provides an incredibly rewarding and relatively accessible experience. It’s considered an “easy hill-fix” with a moderate ascent, making it suitable for many. From its summit, the viewpoint offers fantastic panoramic vistas across north Mull, with views stretching towards Tobermory and even glimpses of other islands like Rum, Eigg, and Coll on clear days. The walk allows for birdwatching, with potential sightings of upland species and Mull’s iconic golden and white-tailed eagles soaring overhead. A circuit around the “Crater Lake” at the summit further enhances the visit, making ‘S Airde Beinn a compelling destination for both geological enthusiasts and casual walkers seeking breathtaking views and a taste of Mull’s wild beauty.