Stratigraphic nomenclature of the Tertiary of western New Mexico and eastern Arizona: An alternative proposal
— Wolfgang E. Elston

I am very grateful to Steve Cather, Jim Rade and Dick Chamberlin for permitting me to review the previous paper (Cather et al., this volume) and to present some alternatives. The six-fold Tertiary classification (T1 through T6) of NMGS (1982) is here proposed as a chronostratigraphic framework (Fig. 1) to which lithostratigraphic units can be attached, in accordance with the stratigraphic code of NACSN (1983). In the Mogollon-Datil volcanic field, boundaries between T2, T3, and T4 are based on dated ignimbrite sheets that do not transgress time lines; their chronostratigraphic boundaries can also serve as lithostratigraphic boundaries. It is further proposed that NMGS sponsor a committee to review the Tertiary terminology of New Mexico and make recommendations on the following issues: (1) The adequacy and validity of proposed chronostratigraphic boundaries, (2) Boundary problems in interfingering volcanic rocks from diverse sources, (3) The placement of arbitrary boundaries between laterally equivalent units with different traditional names, e.g. Mogollon Rim-Baca Formations, Gila-Santa Fe Groups, and (4) The nomenclature of rock bodies, keeping in mind the NACSN (1983) rules regarding establishment and maintenance of type localities, naming of units (with special regard to the rule of priority), and abandonment of obsolete or redundant terms.