Аннотация:"Clay’ interlayers in Upper Cretaceous carbonate rock masses in Mangyshlak are described. The composition of the clays and the types of foraminifera they contain are noted, and the origin of the "clay’ interlayers is explained. The data produced by the study may be used to determine the rate of sedimentation, to reconstruct climatic conditions, fluctuations in sea level, the intensity of erosion, the influence of tectonics and other factors. -translated by P.Cooke