Pg. 27 (table 2), 44 (fig. 3), 47-49. Elephant Butte formation of Armendaris group (both new). Term proposed for all rocks between top of Derry series (new) and base of Whiskey Canyon limestone (new) of Armendaris group. Is a slope-former. Formation is essentially limestone, with one thin bed of conglomeratic sandstone about 22 feet above base and several beds of calcareous, gray, silty, and micaceous shale near middle. Includes Warmington limestone member (new) at base. Thickness at type locality about 82 feet. Is basal formation of Armendaris group. Overlies Cuchillo Negro formation of Mud Springs group (both new). Highly fossiliferous (notably calcareous algae, fusulinid Foraminifera, megafossils). Age is [Middle] Pennsylvanian (Des Moines).
Type locality: western end of Whiskey Canyon [now unlabeled; on west side of Cuchilla Negro Creek], just [east] of westernmost box canyon, in SW/4 sec. 1, T. 13 S., R. 5 W., [approx. Lat. 33 deg. 12 min. 09 sec. N., Long. 107 deg. 18 min. 36 sec. W., Cuchillo 7.5-min quadrangle], north portion of Mud Springs Mountains, Sierra Co., central NM. Named from Elephant Butte, [northeast of Truth or Consequences] in Rio Grande Valley, at Elephant Butte Dam, Sierra Co., central NM.
[Additional locality information from USGS historical topographic map collection TopoView, accessed May 18, 2018.]

Source: Publication; US geologic names lexicon (USGS Bull. 1200, p. 1227).