This special issue of Geological Magazine is dedicated to the memory of Dr Alan Gilbert Smith, Fellow of St John's College and Emeritus Reader in Geology at the University of Cambridge, who passed away on 13 August 2017 at the age of 80. I first met Alan at the 5th International Symposium on Eastern Mediterranean Geology in Thessaloniki, Greece, in spring 2004 and later on several occasions when I was working on the Cambridge Arctic Shelf Programme (CASP) in Cambridge. The palaeotectonic evolution of Greece was one of our common interests. Alan was one of the pathfinders in palaeogeographic research in the 20th century. Together with Sir Edward Bullard (1907–1980) and Jim E. Everett, he published the first computational approach in palaeogeography in their famous paper ‘The fit of the continents around the Atlantic’ (Bullard, Everett & Smith, 1965), which shows a very accurate geometrical fit of the circum-Atlantic continents using the early Cambridge University EDSAC 2 computer. Later, in a contribution in Nature entitled ‘The fit of the southern continents’, Smith & Hallam (1970) presented the first computer fit of the contour of the southern continents forming Gondwanaland. Worth mentioning also are his detailed palaeogeographical maps of the entire Earth, down to epoch level (e.g. Smith, Briden & Drewry 1973; Smith, Hurley & Briden 1981) and his work on the first three editions of A Geologic Time Scale (Harland et al.1982, 1990; Gradstein, Ogg & Smith 2005). Alan's great achievements in the Earth sciences have stimulated new ideas and had a huge impact on geological research, including palaeogeography.