Abstract Some contradictory propositions and concepts of the theory and practice of stratigraphy regarded as paradoxes are discussed. Attention is paid to the fundamental impossibility to associate the wide geographic distribution of a group of organisms with a high rate of speciation of these organisms. However, it is this feature that is commonly used as the basis for determining orthostratigrafic groups of fossil organisms. The dualism of time in stratigraphy, which led to the emergence of chronostratigraphy and the GSSP concept, is considered. The incompatibility of chronological and chronometric datings in stratigraphy is proved. Finally, the paradox of the smallest chronological unit is examined, which is related to the existence of not one but several smallest units (zones) in zonal chronology.