doctrine that explains the differences in fossil forms encountered in successive stratigraphic levels as being the product of repeated cataclysmic occurrences and repeated new creations. This doctrine generally is associated with the great French naturalist Baron Georges Cuvier (Cuvier, Georges, Baron) (1769–1832). One 20th-century expansion on Cuvier's views, in effect, a neocatastrophic school, attempts to explain geologic history as a sequence of rhythms or pulsations of mountain building, transgression and regression of the seas, and evolution and extinction of living organisms.