Исключение стратотипов подразделений из практики конструирования Общей стратиграфической шкалы является серьезной ошибкой, так как стратотипы границ не могут их заменить. Стратотип подразделения и стратотип границы являются дополняющими друг друга характеристиками стратона. В связи с многолетней и детальной изученностью, обилием и разнообразием фауны, хорошей обнаженностью и отсутствием значительных тектонических нарушений наилучшими кандидатами на роль ярусных стратотипов в нижнем кембрии следует считать разрезы Лено-Алданского региона Сибирской платформы. Поэтому для расчленения нижнего кембрия предлагается использовать номенклатуру и стратотипы ярусов (и их границ), соответствующие сибирскому ярусному стандарту.

The Cambrian lower boundary defined at the Tommotian Stage base in Siberia is more plausible than that accepted in the International Stratigraphic Scale. Disadvantages of Siberian sections, which were referred to when the boundary stratotype was selected in Newfoundland, are overstated in fact. A supposed considerable gap in sedimentation between the Tommotian and Nemakit-Daldynian stages was considered as principal shortcoming of Siberian successions. As is established recently, however, the gap at this level in the Siberian platform is not larger than one biostratigraphic zone and cannot be recognized based on paleontological records. The Cambrian lower boundary in Siberia is well substantiated based on small-shelly fossils used to depict in detail the Vendian-Cambrian biostratigraphy. In distinction from the international standard, the boundary level established in Siberia is consistent with available data on the C-isotope chemostratigraphy. The other drawbacks of the international standard are as follows. (1) It is of a doubtful paleontological substantiation. (2) A possibility that biozones of skeletal fossils can be extended downward by zonation of ichnofossils is unproved. (3) Boundaries of the Nemakit-Daldynian Stage identified with the Manykaian Stage are defined incorrectly. (4) The uncertain position of the Nemakit-Daldynian lower boundary means that the Ediacarian Stage is largely or entirely above this level. At present, the Tommotian lower boundary is the reliable oldest level of a high biostratigraphic rank, which is adequate for establishing and tracing the Cambrian lower boundary.

The Vendian-Cambrian sequences recovered by boreholes K-203 and K-204 and by the deep Eiik Hole 343-0 in the North Siberian platform yielded abundant small-shelled fossils characteristic of the N. sunnaginicus Zone of the Tommotian Stage and also of P. antiqua and A. trisulcatus zones of the Nemakit-Daldynian Stage. These sequences appear to be more fossiliferous than the coeval sequence of the reference Markha borehole, which is used for the correlation of natural exposures in the northern part of Siberia with the borehole sections in its inner part. New data enable us to use the recognized stratigraphic subdivisions in the inner oil-and-gas provinces of the Siberian platform and to outline the elaboration method of the general stratigraphic scale for the Vendian-Cambrian boundary beds.