Mancos lies in the southwestern plateau region and features a 216 surface-acre reservoir in Jackson Gulch. Water is delivered to Jackson Gulch from the West Mancos River. Geologic exposures feature the Jurassic-age Brushy Basin Member of Morrison Formation sandstones in Chicken Creek and Jackson Gulch. The Morrison Formation is flanked by Burro Canyon Formation sandstones and conglomerates. Quaternary alluvial and eolian deposits laid down during Pleistocene to recent times cover the eastern portion of the park.