George Greenough was one of the influential group of early nineteenth-century English geologists who rejected both Hutton's and Werner's attempts to propound all-embracing geological theories, and followed a deliberately empirical approach. He travelled through Scotland in 1805, studying geological phenomena in the light of both the Plutonist and the Neptunist theories, and generally concluded that neither was entirely satisfactory as an explanation of the observable facts. He was also the first to suggest that the ‘Parallel Roads’ of Glen Roy were (...) the successive beach-levels of a former lake: this theory was later attacked by Darwin but ultimately vindicated by Agassiz's glacial theory. The more important geological passages from Greenough's MS. journal of the tour are reproduced and discussed in this paper. They illustrate some of the scientific problems that were involved in accepting either Hutton's or Werner's theory entire. (shrink)