The Cuillin () is a range of mostly jagged rocky mountains on the Isle of Skye in Scotland. The main Cuillin ridge is also called the Black Cuillin to distinguish it from the Red Cuillin (), which lie to the east of Glen Sligachan.
The peaks of the Black Cuillin are mainly composed of gabbro, a very rough igneous rock which provides a superb grip for mountaineers; and basalt, which can be very slippery when wet. The rocks forming the ridge of the Black Cuillin (and outliers such Blà Bheinn) are dark, particularly in the shade, but when in sunlight the Black Cuillin can appear grey to brown. The main ridge forms a narrow crest, with steep cliffs and scree slopes. The ridge is about 14 km long (from Gars-bheinn in the south to Sgùrr nan Gillean in the northeast), and curves in an irregular semi-circle around Loch Coruisk, which lies at the heart of the range. The highest point of the Cuillin, and of the Isle of Skye, is Sgùrr Alasdair in the Black Cuillin at 992 m (3,255 ft).
The Red Cuillin are mainly composed of granite, which is paler than the gabbro (with a reddish tinge from some angles in some lights) and has weathered into more rounded hills with vegetation cover to summit level and long scree slopes on their flanks. These hills are lower and, being less rocky, have fewer scrambles or climbs. The highest point of the red hills is Glamaig (775 m), one of only two Corbetts on Skye (the other being Garbh-bheinn, part of the small group of gabbro outliers surrounding Blà Bheinn).
The scenic beauty of the Cuillin has led to it being designated a national scenic area, one of forty such areas in Scotland. A Scottish Natural Heritage review of the special qualities of the Cuillin stated:
Etymology
There are several theories about the derivation of the name Cuillin. One suggestion is that it comes from the Old Norse word kjölen, which literally means the keel of a boat, suggesting a similarity with an upturned Viking longship. Peter Drummond, in Scottish Hill and Mountain Names (1991), noted this is also a name of the Scandinavian Mountains and says it can mean 'high rocky mountain'. Another suggestion is that it comes from Gaelic cuilionn, meaning 'holly', because of the mountains' jagged shape. The name has also been linked to Gaelic mythology, with the hills being the place where Cúchullin learnt archery from the female warrior Scáthach. It is also suggested it may come from a word meaning "worthless" (in an agricultural or economic sense), given their lack of vegetation.
Natural history
The Cuillin are a diverse and complex geological landscape, and there is a clear distinction visible between the two mountain types. The mountains formed from the remains of the magma chambers which fed volcanic eruptions. In the Black Cuillin the rocks cooled to form gabbro, the coarse-grained rock that makes up much of the range. Cracks and fissures in the rock provided pathways for later magma intrusions, leading to dykes of basalt which are commonly seen across Skye. The Red Cuillin also have volcanic origins, being formed from a later intrusion of acidic, granitic rock. This granite was more uniformly eroded by wind and water than the gabbro and basalt, causing the red hills to have smoother outlines.
The Cuillin provide classic examples of glacial topography and were the subject of an early published account by James Forbes in 1846 (who had become a fellow of the Royal Society of Edinburgh aged only nineteen). He partnered Louis Agassiz on his trip to Scotland in 1840 and although they subsequently argued, Forbes went on to publish other important papers on Alpine glaciers. In 1904 Alfred Harker published The Tertiary Igneous Rocks of Skye, the first detailed scientific study of an extinct volcano.
The Cuillin encompasses a wide range of habitats, changing with altitude. At the base there are conifer plantations, coastal woodlands and areas of heather moorland and rough grassland. The lower slopes are covered by various different types of bog, with grassland on the better-drained slopes that are found above 400 m. Higher up, the rocky hills are largely bare, with exposed rock and scree. The entire area is designated as a Special Protection Area under the Natura 2000 programme due particularly for its importance to golden eagles. The site is of European importance for these birds, and holds one of the highest-density populations in Britain, having an unusually high breeding productivity. 11 pairs were estimated in 1992, this representing about 3% of the breeding population in Great Britain at that time.