Locality 266. Exposures in gulley N of dmz and at base of butte south of Bickley Ranch in center W1/2, SW1/4, sec. 15, T18N R23E, Black Horse SE quad., Carson Co, So.Dak. Tancredia-Ophiomorpha biofacies in gulchies N of dmz, grades into grayer Ophiomorpha - bearing ss in lower part of butte which is capped by hard gray O-bearing "Colgate". Complete section of butte not exposed but patches show only sand. Total interval from gulley base to butte top about 75'. No section measured. To south, on road heading E, from Fitzgerald School along S border sec's 22 and 23, T18, R23, float of Hell Creek concretions and chips fossil wood come in on rise in center sec's 22-27, at about El. 2220. To east across draw N road gutter shows rather "bundled" colgate-like friable sand with flat OB ferrug concs and purplish layers with abundant plant frags. Suggests total absence of Bullhead facies; but on road S from 266 to Firststeel a road cut on W side shows mixed Bullhead-Colgate lithology - whether actually interfingering or just local Bullhead lens can't tell from outcrop scale. This cut located on S. side dip across draw, W side road, about 1 mile S of Fitzgerald school (which is in NE cor. sec. 28, T18N, R23E.).