HUECO MOUNTAINS. The Hueco Mountains, a range (centered at 31°57' N, 106°01' W), rise in southern Otero County, New Mexico, and extend twenty-seven miles south into Texas, generally along the El Paso-Hudspeth county line. Cerro Alto Mountain in Hudspeth County, with an elevation of 6,787 feet above sea level, is the highest in the range. Hueco Tanks State Historical Parkqv is on the western flanks of the range, thirty miles east of El Paso. Between the Huecos and the Franklin Mountains to the west lies the Hueco Bolson, a down-dropped area with an elevation of 4,000 feet above sea level, with sedimentary fill nearly 9,000 feet thick. Shallow, stony soils in the Hueco Mountains support oak, juniper, and some mesquite. The mountains were part of the Rocky Mountain trend, forced upward as part of the Laramide mountain-building period during the late Cretaceous, 60 to 70 million years ago. Hueco is Spanish for "hollow."
Darwin Spearing, Roadside Geology of Texas (Missoula, Montana: Mountain Press, 1991).