First called upper shale member (informal) of the Kirtland by Reeside (1924), which he applied to siltstone, mudstone, and sandstone between Late Cretaceous (Maastrichtian) Farmington Member and Paleocene (Danian) Ojo Alamo Sandstone. Here formally named as next highest member of Late Cretaceous (early and late Maastrichtian), broadly fluvial Kirtland Formation (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). De-na-zin type area outcrops occur in NW1/4 sec 19, T24N, R11W, Alamo Mesa East 7.5-min quad, San Juan Co, northwestern NM. Name origin not stated. Pervasive and mappable, this unit consists of green mudstone, siltstone, and minor sandstone; mudrocks in its upper part show high volcanic content. The De-na-zin has been mapped in and around type area by J. L. Brown, 1982, and is published as Geologic Map of the Alamo Mesa East Quadrangle, San Juan County, New Mexico: USGS Miscellaneous Investigations Map MF-1497, scale 1:24,000. Thickness in type area is 30 m. Conformably overlies the Farmington until the Farmington pinches out to the southeast so that the De-na-zin and the Hunter Wash become inseparable. Forms slope break between the Farmington and basal conglomerate of the Naashoibito. 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).