The article is devoted to the 120th anniversary of Nikolay Bronislavovich Vassoevich (1902–1981) – a famous petroleum geologist, professor, corresponding member of the USSR Academy of Sciences. The article recalls his significant achievements in the field of fundamental geology. The first and main work in this field was his monograph on the methodology for studying the sedimentation cyclicity of flysch strata (1948), with the continuation of the topic in the next book, published in 1951. The scientific heritage of N.B. Vassoevich, who headed the Petroleum Geology Department of Lomonosov Moscow State University in 1963–1981, is preserved and developed in the modern educational and scientific activities of this Department. Teachers, staff and students with deep gratitude and respect honor the memory of N.B. Vassoevich, using his methodological recommendations on sedimentation cyclicity both in the training course of lithofacial analysis and applied in practical work in the study of oil and gas bearing strata of sedimentary rock basins. A huge role in the development of the terminology of this theory is associated with the development of the conceptual base of this geological direction. Professor N.B. Vassoevich had invested continuous work on the creation of systematic and logical classifications according to the composition, structure, genesis and hierarchy of geological sedimentary bodies that make up oil and gas bearing rock complexes.