A simple field and laboratory classification of sedimentary rocks is proposed. It is based fundamentally on composition and texture, with the primary divisions determined by the mode of origin of the constituents. Tt is tripartite in nature, consisting of (1) a dominantly fragmental division, including conglomerates, sandstones, and shales; (2) a division represented by rocks which are partly fragmental and partly precipitated, including ironstones, silicastones, coal, limestones, and dolostones; and (3) a division of salinastones, which are dominantly precipitated but may possibly be fragmental. The several new terms in the classification were first proposed in a paper read before the Chicago meeting of the Geological Society of America in December, 1946 (Shrock, p. 1231).