uniformitarianism, in geology, doctrine holding that changes in the earth's surface that occurred in past geologic time are referable to the same causes as changes now being produced upon the earth's surface. This doctrine, the basic concept of which was first advanced by the Scottish geologist James Hutton in his Theory of the Earth (1785, 1795), was further expounded by another Scotsman, John Playfair, in his Illustrations of the Huttonian Theory (1802). It made little progress, however, against the teachings of the school of Abraham Gottlob Werner, a German geologist, and as a theory of dynamic geology it was overshadowed by the doctrine of catastrophism, of which the major supporter was the French naturalist G. L. Cuvier. This was in large measure because uniformitarianism seemed in several ways to be contrary to religious beliefs. It required an immensely long period of time for the consummation of geological processes (thus disturbing the accepted biblical chronology) and set aside all remarkable catastrophies (thus, it would seem, denying the Flood). Uniformitarianism had its day in the 19th cent., when it was widely accepted as a result of the efforts of the English geologist Sir Charles Lyell. The more recent tendency has been to effect somewhat of a synthesis of the two theories, based mainly upon Lyell's conception of the slow operation, over extremely long periods of time, of forces at work in historic time, but admitting the existence in earth history of periods when such activity was accelerated and intensified.