Chinle formation divided into two mapped units in this report: Correo sandstone member, at top (here named), and an unnamed red shale member, at base. No type locality designated. Only outcrop of Correo is along the lower bench at south edge of Mesa Gigante, Valencia Co, NM in San Juan basin. Upper contact of Correo slightly uneven owing to erosion prior to deposition of Wingate sandstone, which disconformably overlies it. Correo is dark-brown and buff, medium to massive, cross-bedded sandstone, 90-120 ft thick. Underlying unnamed red shale member consists of red-brown soft shale, 1,000 +/-ft thick; basal part not exposed. The weak red shale member is the unit most susceptible to erosion in the area, and most of the estimated section is covered by alluvium and landslide material. It appears, however, to underlie the northwest half of Mesa Lucero and the broad San Jose Valley from near Lucero Spring northward to base of Mesa Gigante. Probably it is present also in many isolated outcrops along the Comanche thrust and the Santa Fe faults, but in such occurrences positive identification cannot be made because of the presence of similar shale in underlying Shinarump conglomerate. Measured sections, cross sections, and geologic map. Late Triassic in age.

Source: GNU records (USGS DDS-6; Denver GNULEX).

Reduced in stratigraphic rank from Correo Sandstone Member of Chinle Formation to Correo Sandstone Bed of Petrified Forest Member of Chinle Formation. Change in rank deemed necessary because Correo is both overlain and underlain by rocks of the Petrified Forest. Occurs only along south side of Mesa Gigante in sec 20, T9N, R3W, Valencia Co, NM in San Juan basin, where the bed is 62.5 ft thick. Consists of: 1) pale-olive (gray weathered) conglomerate with coarse grains to cobbles of gray limestone, red-gray siltstone, and gray sandstone in a matrix of very fine to fine-grained, fair-sorted sand, and has some green mica at base; and 2) an overlying red (pink weathered) fine- to medium-grained, fair-sorted sand composed of subangular quartz and gray to olive conglomerate of gray to white siltstone and limestone in a sand or limy silt matrix in a measured section at Mesa Gigante. Of Late Triassic age.

Source: GNU records (USGS DDS-6; Denver GNULEX).