Abstract Evaporites were classified on the basis of their environmental relationships, particularly with respect to the under- and over-lying sedimentary sequences. The scope of knowledge that went into establishing this classification was limited to deposits developed in cratonic (continental crust) areas of the world. The advent of the concept of sea-floor spreading, together with new data collected by the Deep Sea Drilling Project and extensive submarine seismic surveys, both on the continental margins and in the deep-sea, enables us to classify evaporitic sediments on the basis of tectonic settings as well as sediment affinities. The various divisions are in a sense artificial; the one classification readily overlaps with the other, and each of the groupings may grade through time and space.