‘Geological Map of the Islands’, in John Macculloch, A Description of the Western Islands of Scotland, Including the Isle of Man: Comprising an Account of their Geological Structure: With Remarks on their Agriculture, Scenery, and Antiquities

John MacCulloch, geologist to the Ordnance Trigonometrical Survey, spent each summer from 1814 to 1821 examining the geology of rocks around hundreds of survey stations on Scottish peaks. His description of the Western Isles pioneered a new understanding of crystalline rock origins and of the power of erosion. His controversial later book 'The Highlands and Western Islands of Scotland' (1824), however, advocated the clearance of ‘lazy’ highlanders and met with virulent opposition.