by the uplift. Once exposed, the natural forces of wind and rain slowly stripped away the softer sediments, further uncovering the ancient reef and revealing the sheer limestone walls of the Guadalupe Mountains. Human history Deep in the Chihuahuan Desert, the area around El Capitan is composed of rugged mountains and wind-swept salt flats. As a result, most of the Native American presence in the vicinity was centered around 3 miles southeast of El Capitan in the area now called Pine Springs. An oasis of springs, seeps, and vegetation, this area exhibits evidence (mescal dumps, petroglyphs, artifacts, etc.) of human occupation for several centuries. Most recently, the area was a seasonal home to bands of the Mescalero Apache, who, steadily pushed south by the fiercely expansionist Comanche in the 18th century, used their local knowledge of springs and other scarce resources to maintain themselves in an otherwise harsh environment well into the 19th century, when Anglo expansion and settlement ended their delicately balanced way of life. While the occasional Spanish expedition, such as that of Antonio de Espejo in 1582, came close to the area around El Capitan, permanent Anglo-European presence in the area dates from the late 1840s, when the region officially became a part of the United States after the American victory in the Mexican–American War. Eager to find a suitable trail from San Antonio to El Paso, and eventually the far-flung American territories on the Pacific coast, a number of expeditions pushed into the hot, dry, dangerous lands west of the Pecos, hoping to find a potential wagon route with enough timber and water to make consistent travel possible. One of the expeditions, led by Indian Agent Robert S. Neighbors, made its way to El Paso in 1849 through a difficult journey that required crossing and recrossing the Pecos and Devil's Rivers, and then surviving the long, dry stretch from the Davis Mountains to El Paso. Dismayed at the prospect of returning by the same route, the party instead struck off east from El Paso towards the Hueco Tanks and Guadalupe Pass, which they hoped to follow to an established crossing of the Pecos River near the modern Texas-New Mexico border long used by Mexicans and Native Americans. Successful in reaching the Pecos, Neighbors quickly descended the river and made his way back to San Antonio, where he reported to his superiors that this route offered good