The Gothic and Maroon formations are the most significant Upper Paleozoic lithogenetic units between Copper Creek and Glenwood Springs, Colorado. Thin limestones were traced southward from Glenwood Springs to Redstone and furnish local horizons of time-rock correlation. They do not, however, mark the limits of useful lithogenetic units. The projected horizons of the Schoolhouse sandstone and the South Canyon Creek dolomite occur about 2,000 feet below the pre-Jurassic unconformity near Carbondale, where their position is occupied by laterally equivalent redbeds.

A local basin in the Central Colorado basin in the Carbondale area is suggested by gypsum accumulation, marked thickening of the Maroon formation, and a pre-Jurassic structural basin. Restriction of the Central Colorado basin in the Treasury Mountain dome area is indicated by basal conglomerate in the Belden shale, abundant reworked Pennsylvanian rocks in the Maroon formation, marked thinning of the Maroon formation, non-deposition of marine tongues within the Maroon formation, and a pre-Jurassic structural high.

Lateral equivalence of the upper Maroon and lower State Bridge siltstone is suggested by intertonguing finer-grained redbeds in the eastern outcrops of the upper Maroon formation.