A laying time of Minusinsk' cavities, dispersed groove genesis conjugated with it, subalkaline and alkaline volcanism has been revised and determined as medium Ordovician period. This fact calls into question the essentials of all system of the geological evolution history of Altai-Sajan folded region in Paleozoic era. The research is undertaken for additional study of log structure of the byskar series lower part to substantiate its age on the basis of U-Pb isotope dating. International stratigraphic scale is used in age determination.
