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Georges Louis Leclerc comte de Buffon (1817). “A Natural History, General and Particular: Containing the History and Theory of the Earth, a General History of Man, the Brute Creation, Vegetables, Minerals, Etc. Etc”, p.6
William Wordsworth, Adam Sedgwick (1853). “A complete guide to the Lakes, comprising minute directions for the tourist, with mr. Wordsworth's Description of the scenery of the country, &c. and Three letters upon the geology of the Lake district, by prof. Sedgwick”, p.183