Blancan Mammalian Fauna and Pleistocene Formations, Hudspeth County, Texas

Vertebrate fossils representing a new Blancan local fauna occur in the Fort Hancock Formation (new name) and the Camp Rice Formation (new name), Hueco Bolson (Fig. 1) Hudspeth County, Texas. Fossils indicate the Fort Hancock Formation and the lower part of the Camp Rice Formation are probably Aftonian in age. Pearlette volcanic ash dates the middle of the Camp Rice as late Kansan. It also provides a precise horizon for correlating the Pleistocene stratigraphic section of the Great Plains with that in the Hueco Bolson. The Fort Hancock Formation is composed of clay, silt, fine sand, and gypsum. Silt, sand, gravel, some clay, and volcanic ash characterize the Camp RiceFormation. An unconformity separates the formations. The Fort Hancock was deposited in a closed basin, but the Camp Rice represents fluvial and floodplain deposition by the Rio Grande after it developed as a through-flowing stream in the Hueco Bolson during late Kansan.