First called lower shale member (informal) by Reeside (1924), which included all fine-grained strata between Fruitland Formation and Farmington Sandstone Member of the Kirtland Formation (all Late Cretaceous). Here named as next lowest member of the Late Cretaceous (early and late Maastrichtian), broadly fluvial Kirtland (revised). Members of the Kirtland, ascending, are Bisti (new), Hunter Wash (new), Farmington (redescribed), De-na-zin (new), and Naashoibito (as used by Baltz and others, 1966). Type section is along Hunter Wash in secs 23-26, 27-28, 33-34, T24N, R13W, and secs 8-9, 16-20, T24N, R12W (Reeside, 1924, plate 2, section 15), San Juan Co, northwestern NM. Named for local wash rather than for Hunter Wash local fauna proposed by Clemens (1973), and then used by Lehman (1981), as well as several others. The paleontological term is abandoned here and not to be confused with the rock-stratigraphic term, Hunter Wash Member. Consists of green and gray siltstones and mudstones, white lenticular, cross-bedded sandstone, minor thin (<1 m thick) carbonaceous mudstones and coals, and rare, thin air-fall volcanic ashes. Total thickness in type area is about 375 m. Conformably overlies the Bisti and conformably underlies the Farmington. Age is Late Cretaceous (early Maastrichtian) based on vertebrate fossils, as well as on radiometric dates, palynology, and stratigraphic position. Report includes geologic sketch map, fossil lists, and stratigraphic column.

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