A sequence of transgressive-regressive events and faunas of conodonts and ammonoids from
      relatively deep-water deposits of the Ust'-Yarega, Domanik and Lyaiol Formations have been
      studied.  In dividing these stratigraphical subdivisions local conodont zones have been used;
      these were correlated with Ziegler's conodont zonal scale.  The max imum transgression corre-
      sponds in time to the period of the Domanik Formation (the interval from Middle asymmetrica
      to triangularis Zones).  Dating of regressive events is closely similar to those described by
      JOHNSON & SANDBERG (1989).  A decrease in species variety of conodonts and ammonoids sug-
      gests correlation with phases of regression of the sea basin and increasing diversity correlates
      with periods of transgression.  The greatest changes in the composition of faunal complexes are
      observed at two levels: firstly at the boundary of the Ust'Yarega and Domanik Formations;and
      secondly at the boundary of the Lower and Middle Member of the Domanik Fomation.  Great
      changes in the relief of the sea floor (the formation of non-compensated depressions) and a
      change in geochemistry of the near-bottom water, correspond to the first level.