Geology and vertebrate paleontology of Cretaceous and Tertiary strata on the Pitcock Rosillos Mountain Ranch, Brewster County, Texas

The Late Cretaceous Pen, Aguja and Javelina Formations and Tertiary Black Peaks, Hannold Hill and Canoe Formations are exposed on and around the Pitcock Rosillos Mountain Ranch, adjacent to Big Bend National Park, Texas. The objectives of my project were to produce a geologic map of these sedimentary strata on and around the Rosillos Mountains laccolith and to collect fossil vertebrates from the units of interest. I worked on unmapped areas of the Pitcock Ranch and tested the validity of the geologic map of the park produced by Maxwell et al. (1967) where it falls on the ranch. Numerous differences were found between the Maxwell et al. (1967) map and my observations, while many features coincide. The geologic map produced is important because it includes previously unmapped areas and revisions to a previously constructed map of the area.