4 January 2021
The Trotternish landslide complex on the Isle of Skye in Scotland
A few years ago I posted briefly about the Quiraing landslide (also sometimes spelt Quirang) on the Isle of Skye in Scotland, suggesting that it is the most beautiful landslide complex in the world. I stand by my view (but would welcome alternative suggestions of course). It is hard to beat this in my views:-
In fact the Quiraing is one part of a huge, ancient landslide complex located on the east side of the Trotternish peninsula in the northern part of the Isle of Skye. This landslide complex should be better known, but it is a long trip to visit it even from the major cities of Scotland. The complex, which is not active, dates from the period after the last glaciation, between about 13,000 and 5,000 years before present. The Google Earth image below shows the Trotternish peninsula and the location of the two best known landslides, the Quirang and the Storr:-
As the image shows, the Trotternish peninsula is dominated by a large escarpment running apprixmately north-south, formed from Tertiary basalts. At the Storr this has an elevation of about 720 metres. This escarpment, which extends for 23 km, has ancient landslides along its whole length. This is the complex known as the Trotternish landslides – it is the largest landslide complex in the UK by far.
Colin Ballantyne of the University of St Andrews wrote an excellent summary of this complex (Ballantyne 2008), which was published in the Scottish Geographical Magazine. He included this very nice summary of the general structure of the landslides at Trotternish:
As the diagram shows, these landslides consist of rotational failure through the basalt escarpment and the underlying Jurassic sediments, with the basal shear surface being defined by a resistant dolerite sill within the Jurassice rocks. There are multiple failures at the various sites, with the blocks buttressing those upslope. The rotated blocks become more degraded downslope.
This is a classic rotational landslide system, on a very large scale.