HORSE MOUNTAIN. Horse Mountain is fourteen miles southeast of Marathon in northeastern Brewster County (at 30°02' N, 103°07' W). Its summit, at an elevation of 5,013 feet above sea level, rises 1,375 feet above Peña Blanca Creek, 1½ miles east. Horse Mountain is characterized by intricate folds and turns of white Caballos and dark Maravillas outcrops, which exemplify the intensely deformed character of the Marathon uplift. Soils on the mountain are shallow and stony and support scrub brush, creosote bush, cacti, grasses, oak, mesquite, juniper, and piñon pine.