Falls of Clyde and Carstairs Kames: glacial meltwater rivers shape the landscape

The Falls of Clyde and Carstairs Kames are excellent examples of the effects of glaciation and the powerful role of glacial meltwater rivers in shaping the landscape

The Falls of Clyde at Bonnington Linn.
Image: Lorne Gill/Scottish Natural Heritage.

Around 15,000 years ago, melting of ice released vast volumes of meltwater into rivers. These rivers carved new channels into bedrock and deposited large accumulations of sand and gravel, often in the form of ridges and mounds.

The spectacular rock-cut gorge and waterfalls along the River Clyde, south of Lanark, are excellent examples of landforms resulting from the glacial diversion of drainage. In its middle reaches, the River Clyde flows northwards, meandering gently across a wide floodplain. South of Lanark, however, the river changes dramatically in character, entering a 7-kilometre-long bedrock gorge up to 50 metres deep with rock steps and waterfalls cut into Devonian sandstone. During the most recent glaciation, the original channel of the river was infilled with glacial deposits, damming the river and creating a large lake upstream. When the water burst through, it cut a new channel at a higher level, resulting in a steeper course as the river descended to rejoin its former route to the north.

This new course includes major waterfalls – by volume the largest in Britain – Cora Linn (a three-step fall, 25 metres high) and Bonnington Linn (10 metres high), where beds of relatively resistant sandstone overlie weaker mudstone. To the north, there are two further waterfalls, at Dundaff Linn (3 metres high) by New Lanark and Stonebyres Linn (24 metres high) west of Lanark. This is the most dramatic example in Scotland of the disruption of a major river course by glacial deposition. It is also unusual in Scotland to find such spectacular waterfalls in the lower reaches of large rivers.

The Falls of Clyde became a major attraction for visitors in the late-18th and 19th centuries, when natural features, such as waterfalls, were the epitome of sublime and picturesque scenery. Leading artists and literary figures, including the Wordsworths and J.M.W. Turner, helped to promote the Falls as an essential destination on the then fashionable ‘Scottish Romantic tour’. On viewing Cora Linn with her brother, William, and Samuel Taylor Coleridge on their tour of 1803, Dorothy Wordsworth wrote that “[t]he majesty and strength of the water …… struck me with astonishment.”

In the late 18th century, the waters of the River Clyde powered the cotton mills at New Lanark, now a World Heritage Site that includes the gorge and the waterfalls in its buffer zone. Later, in 1927, the river was harnessed again for the first large-scale hydro-electric power station in Britain. Water was diverted from above the Falls via an underground pipeline to the power station below. There are open days when the power station is switched off, allowing the full volume of the river to flow over the falls; this is when the “sublime horrors” that attracted Victorian visitors can be fully appreciated.

Carstairs Kames forms part of an extensive glacial drainage system extending in a belt from south west of Lanark to north east of Carstairs. Where meltwater rivers flowed in confined tunnels beneath the glaciers, their former routes are sometimes traced out in ridges of sand and gravel (or ‘eskers’) left behind when the glaciers melted. The landforms at Carstairs consist of a series of sinuous ridges and mounds of sand and gravel with intervening kettle holes. Despite a long history of study, the exact origin of the Carstairs landforms remains a matter of debate, in particular whether the eskers formed in tunnels under the ice or in more open channels cut into the surface of decaying ice. A significant part of the original landform complex has been removed by sand and gravel quarrying, leaving only a core area now protected as a Site of Special Scientific Interest. Carstairs Kames are on private farmland but can be viewed from adjacent roads.

Text contributed by John Gordon

Find out more
Scottish Wildlife Reserve information: https://scottishwildlifetrust.org.uk/reserve/falls-of-clyde/
Gordon, J.E. (1992). Carstairs Kames. In: Gordon, J.E. & Sutherland, D.G. (Eds), Quaternary of Scotland. Geological Conservation Review, Series No. 6. Chapman & Hall, London, 544-549.
Gordon, J.E. (2012). Rediscovering a sense of wonder: geoheritage, geotourism and cultural landscape experiences. Geoheritage, 4, 65-77.
Huddart, D. & Bennett, M.R. 1997. The Carstairs Kames (Lanarkshire, Scotland): morphology, sedimentology and formation. Journal of Quaternary Science, 12, 467-484.
McKirdy, A.P., Gordon J.E. & Crofts R. (2007). Land of Mountain and Flood: the Geology and Landforms of Scotland. Birlinn Press, Edinburgh.
Thomas, G.S.P. & Montague, E. 1997. The morphology, stratigraphy and sedimentology of the Carstairs Esker, Scotland, U.K. Quaternary Science Reviews, 16, 661-674.
Werritty, A. & McEwen, L.J. (1997). Falls of Clyde, South Lanarkshire. In: Gregory, K.J. (Ed.), Fluvial Geomorphology of Great Britain. Geological Conservation Review, Series No. 6. Chapman & Hall, London, 33-35.

Aerial view of the Carstairs Kames esker system.
Image: P&A Macdonald / © SNH 2017.

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