Sir Archibald Geikie (1835–1924), one of the towering figures in the history of British geology, maintained a long professional relationship and correspondence with pioneering American geologists of the nineteenth century, including James Dwight Dana, Clarence Dutton, Ferdinand Vandeveer Hayden and Grove Karl Gilbert. Geikie made two trips to the USA. Geikie’s first trip, accompanied by his former student at Edinburgh Henry Drummond, took place in August–November 1879 for field excursions in the American ‘Far West’, including Colorado, Utah, Wyoming, Idaho and Montana, where he could find ample evidence for the dominant role of fluvial erosion in the denudation of continents (a school of thought called ‘fluvialism’ or ‘erosionalism’). These geological excursions also resulted in nine articles by Geikie published during 1880–82 as well as a large number of landscape paintings and sketches now preserved at the Haslemere Educational Museum in England. Geikie’s second trip from April to May 1897 was due to an invitation to deliver a series of lectures on ‘The Founders of Geology’ at Johns Hopkins University; these lectures became the basis for his classic book of the same title. Geikie kept an active interest in geological mapping and discoveries in the USA, as evident from his numerous references to American geology in his 1882 Text-book of Geology. Geikie’s American connections demonstrate that geology, although primarily a field-based regional science, did not evolve in isolation in various countries during the nineteenth century, but that there was lively exchange and synergy in geological research and findings among geologists working in Europe, the Americas and Asia.