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The Precambrian–Cambrian boundary problem in Siberia and some general problems of stratigraphy (Preliminary Report)

Summary Two regions are considered to be the best for the definition of the Cambrian lower boundary in Siberia – in Yakutia (the middle course of the Aldan River), in Western Prianabarye (at the Kotuikan and Kotui). The stratigraphical relationships in these 2 regions are described. Some general problems of stratigraphy are then raised (a) the need to use lithologic-facies, palaeogeography and biostratigraphy together, (b) the boundary stratotype method of delimiting chronostratigraphical subdivisions and (c) the earliest trilobite zones, the Ediacara fauna and geochronology.