geological stage(Technically, a stage is a succession of rock strata laid down in a single age on the geologic timescale.: Толща горных пород, образовавшуюся в течение одного геологического векаMichaelBurov)
the Serpukhovian(The Serpukhovian is in the ICS geologic timescale the uppermost stage or youngest age of the Mississippian, the lower subsystem of the Carboniferous. twinkie)
