Cerro Castellan rises 3293 feet above the desert floor. The Ross-Maxwell Scenic drive takes you around this ancient volcanic peak,
composed of stacked volcanic rocks, including ash, lava, and tuffaceous rocks.
It is capped by a dense lava flow underlain by various tuffs and basalts. A northwest-trending fault cuts the eastern flank of Cerro Castellan.
Though little vegetation grows on the sheer cliffs and steep, pointed profile of its peak, the lower slopes of Cerro Castellan support
a sparse growth of Chihuahuan Desert scrub, including most prominently such characteristic species as creosote bush and ocotillo.