A mountain in Dumfries and Galloway, Cairnsmore of Carsphairn rises to a height of 797m (2612 feet) nearly 4 miles (6.5 km) northeast of Carsphairn. Classified as a Corbett, it is also known as Cairnsmore of Deugh. Its summit is marked by an Ordnance Survey primary triangulation pillar installed in 1936 for the re-triangulation of Great Britain. Geologically, Cairnsmore of Carsphairn is at the centre of an igneous complex, which extends to the neighbouring summits of Dunool (541m), Black Shoulder (688 m), Beninner (710 m) and Moorbrock Hill (650 m). This is by far the smallest of the four plutonic masses injected into the Silurian sedimentary rocks of SW Scotland around 400 million years ago. This complex comprises granite, enclosed within a finer grained granite-tonalite, with a metamorphic aureole extending into the surrounding Silurian conglomerates, grits, greywackes and shales. The other igneous complexes lie to the south and southwest at Cairnsmore of Fleet, Loch Doon and Criffel.