Abstract

Several factors have caused problems in the formal naming of lithostratigraphic units (formations, members, groups) in southwestern Wyoming.

These include:

(1) Vagueness of definitions by geological pioneers in the area.

(2) Geographic isolation from better studied areas.

(3) Pre-Upper Cretaceous strata tend to crop out only in structurally complex situations.

(4) Proximity to Colorado, Utah and Idaho state lines with traditional reluctance to carry names across boundaries.

(5) Position of the region during most of Phanerozoic time at or near the hingeline between stable platform and geosynclinal tectonic environments with resultant complexity of sedimentary facies.

(6) Errors in proper application of the rules governing stratigraphic nomenclature.

The stratigraphic committee has made an intensive study of lithostratigraphic terminology used in the region with the aim of correcting technical errors and reducing of the number of names in use by elimination of synonyms. The law of superposition and the principle of priority in publication are followed rigorously.

The result has been clarity of usage, simplification of terminology and the bringing of local nomenclature into harmony with the Stratigraphic Code. The Committee recommends that for various reasons many names used in the area be abandoned to be replaced with more valid ones from adjoining areas. The rejected names include: Mission Canyon, Wells, Morgan, Weber, Ankareh, Dakota, Thermopolis, Muddy, Aspen, Cody, Baxter, Fort Union, Wasatch and Washakie.