Sandstone of the cyclothems of the Yoredale series is sheet sandstone which consists of tongues of massive cross-bedded sandstone lying on and laterally grading into continuous flaggy sandstone. Each tongue of massive sandstone has its origin in the bank of a channel sandstone, and the radially distributed cross-bedding can be used to locate the point of origin. Local relief existing before sandstone deposition and relief created by sandstone deposition can be demonstrated. The latter often caused emergence which is revealed by the occurrence of seat-earths, coals, and sandy patches in the overlying thin limestone. The features described closely compare with the crevasse deposits in the Mississippi delta and are assumed to be of deltaic origin.