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Cairngorms

The Cairngorm Mountains are well known on many fronts. It is home to sub-arctic plants and birds, has yielded gem-quality minerals and offers a 'playground' to the winter outdoor enthusiast. But to the geomorphologist, the area exhibits classic examples of glacial, periglacial and post-glacial features. Studying these features has helped geomorphologists to understand how glacial processes occur and how the Scottish glacial landscape has developed.

The geology of the Cairngorms has played a crucial role in the landscape's development. The mountains are the eroded remains of a massive body of magma that rose upwards in the crust during the Devonian. At a depth of about 6km, the magma cooled to form granite, however subsequent uplift and erosion brought the granite to the surface by about 50 Ma. As granite is a hard rock resistant to erosion, it formed a broad plateau, while the surrounding rocks continued to be eroded.

The last major ice age to affect the Cairngorms peaked around 20,000 - 18,000 years ago and ended approximately 13,000 years ago. During this time, the Cairngorms were entirely covered by an ice sheet. However, the area was also affected by the Loch Lomond Readvancement, a phase of glacial activity that occurred approximately 11,000 to 10,000 years ago. This later event resulted in the formation of numerous small glaciers in the corries and valleys.

The landforms seen today have formed as a result of the following processes:

• Pre-glacial erosion: relict valleys, weathered bedrock and tors
• Glacial erosion and deposition: glacial breaches (e.g. Loch Avon and the Lairig Ghru), corries, moraines and erratics
• Glacial meltwater erosion and deposition: meltwater channels, kettle holes and eskers
• Periglacial activity: blockfields, blockslopes, patterned ground (stone circles) and solifluction lobes
• Slope and recent activity: protalus ramparts, avalanche landforms, debris flows and loss of vegetation

Further reading:

Gordon, J., Brazier, V., Keast, S. & Threadgould, R. Cairngorms - A Landscape Fashioned by Geology. Produced by: Scottish Natural Heritage & British Geological Survey.

Gordon, J.E. & Sutherland, D.G. 1993. Quaternary of Scotland, Geological Conservation Review Series No. 6., Joint Nature Conservation Committee, Peterborough.

Gordon, J.E. Wignall, R, Brazier, V. and Bruneau, P. 2006. Cairngorms - A Landscape Fashioned by Geology. Produced by: Scottish Natural Heritage & British Geological Survey.