One of the key sections of the Lower Cambrian of the Siberian Platform, the Sukharikha River section, Igarka region, has been described within the interval Upper Vendian - Lower Cambrian, including the Sukharikha, Krasny Porog, and Shumny Formations. For the first time the Sukharikha Formation was completely paleontologically characterized by trace fossils of soft-bodied organisms and calcareous algae. It was shown once more that the Vendian - Lower Cambrian boundary is correctly drawn 1.5 - 2.0 meters below the roof of the Sukharikha Formation, at the base of the Tommotian Stage, consisting of three archaeocyathid zones comparable with type locality zone at the Aldan and Lena Rivers. To correlate the Krasny Porog Formation, poorly characterized by archaeocyatids and trilobites in the part referred to the Atdabanian Stage, the authors have recognized accessory stratigraphic subdivisions - beds with small shelly fossils (SSF). The rocks of the Krasny Porog and Shumny Formations developed under evolving transgression in the basin leading to the disappearance of algae-archaeocyatid organogenic buildings and formation of black shales.
