Выпуск: 2 , Том: 23 , Год издания: 1982

The Ordovician-Silurian boundary layers in Gornyi Altai are described in the region of Ust-Chagyrka. The Llandoverian part of the cross section is viewed as a standard for the Lower-Middle Llandoverian graptolite zones of this region. The variations in the indices of the restored graptolite assemblages at the boundaries of the zones are discussed. Confidence intervals of accuracy for the boundaries drawn between the zones are defined as a percentage of the thicknesses of the boundary zones, and also in absolute time.