Stratigraphic studies across southern Nevada have resulted in reappraisal and suggested revision of the zones of the Whiterock Stage of Cooper (1956), the Rhysostrophia zone being reassigned to his Marmor Stage. The Palliseria zone is revealed as an assemblage closely allied to lithic facies. The zone transgresses other zones based on brachiopods and is younger on the west than on the east.
Dating based on these revised zones indicates upward migration of several lithic facies in a westerly direction. In addition, sands which later comprised the Eureka Quartzite may have moved southward along the miogeosyncline, seemingly from a northern rather than an eastern source.