For many years, the stratigraphic scheme of the Permian deposits of the Urals has been based on the scheme of D. M. Rauser Chernousova [1940]. It was developed in accordance with the distribution of individual foraminifera assemblages along the section. Many of the horizons identified by D. M. Rauser Chernousova have retained their names and have been adopted in the Unified Scheme of Permian deposits of the Urals of 1962, and their sections are considered stratotypic.