The Ardnamurchan Volcano - 4

The Ardnamurchan volcanic event occurred in three phases, each developing around a Centre. The central point of Centre 1, the most easterly of the three, was located in the broken landscape to the west of Meall nan Con, about where Meall Meadhoin now stands. The '1' on the map therefore marks the centre of the first collapsing Caldera, with much of the more westerly evidence destroyed beneath the later Centres 2 and 3.

Centre 1 produced all the classic features: huge emplacements of basaltic rock intruded as Ring Dykes (in red on map), of which Ben Hiant is the most visible, accompanied by agglomerates, lavas and ash flows (purple), and an outer circle of Cone Sheets (orange).

This photograph looking across Kilchoan Bay from Ormsaigbeg clearly shows the huge Ring Dykes that form Ben Hiant itself and the distinctive ridge of Beinn na h-Urchrach to its left. The lump of Maclean's Nose on the right is largely formed of Vent Agglomerates.

The high ridge that runs along the back of Kilchoan village, Glas Bheinn, is part of another Ring Dyke, while the valley to the right, which separates Glas Bheinn from the Ben Hiant complex, is formed of softer rocks which were more deeply eroded by the ice.

The north-south running Ring Dyke, lying immediately to the east of Meall nan Col on the map, forms the heights of Beinn an Leathaid and Cathair Mhic Dhiarmaid, and the ridge which runs along the west of the road from the Cairn down to Kilmory. Lastly, the broken high ground to the west of Fascadale ('F' on map) is also part of a Centre 1 Ring Dyke.

A map of the area is here.