Bison Antiquus occurrence and Pleistocene-Holocene stratigraphy, Canada del Buey, Pajarito Plateau, New Mexico
— Paul G. Drakos, Steven L. Reneau, and Gary S. Morgan

A Bison (probable Bison antiquus) distal humerus fragment was found within a Pleistocene colluvial deposit on a hillslope above Cañada del Buey near White Rock, New Mexico. The Bison fossil was preserved within a buried soil with an inferred age of ca. 50-100 ka, based on soil properties and on stratigraphic position below a deposit of ca. 50-60 ka El Cajete pumice. This represents the second oldest dated Bison in New Mexico, and one of the few occurrences of this genus in the northern mountains of the state. It is also only the second record of a Pleistocene vertebrate from Los Alamos County, and is a rare occurrence of a pre-25 ka Bison fossil in good stratigraphic context. Hillslopes in the study area are underlain by a sequence of truncated Pleistocene and Holocene soils that are inferred to represent colluvial deposition and soil formation followed by erosion in the mid-Pleistocene, the late Pleistocene, and the mid- to late Holocene. The surface soil is developed in deposits that overlie 600-800 yr-old Ancestral Puebloan sites. Colluvium is dominated by relatively fine-grained (fine to very fine sand) slopewash colluvium deposited by overland flow, but also includes rocky colluvium on hillslopes below mesas. The fine-grained colluvium is likely derived mainly from reworking of eolian deposits. Episodic colluvial deposition appears to, at least in part, accompany and follow episodic eolian events, with intervening periods dominated by erosion and the development of truncated soils.