the Permian period. The Guadalupian epoch of the Permian period is named for these mountains, and the Capitanian age within this epoch is named for the Capitan reef. For details on the area's geology, see Delaware Basin. As the range is built up almost entirely of limestone, upland areas have little or no surface water. The only significant surface water is McKittrick Creek, in McKittrick Canyon, which emerges from the eastern side of the massif, just south of the New Mexico border. Elevations at the base of the range vary from above sea level on the western side to on the east. Several peaks on the southern end exceed . The Guadalupe Mountains experience relatively hot summers, calm, mild autumn weather, and cool to cold weather in winter and early spring. Snow storms, freezing rain, or fog may occur in winter or early spring. Frequent high-wind warnings are issued during winter through spring. Late summer monsoons produce thunderstorms. The nights are cool, even in summer. Geology The Guadalupe Mountains are underlain by Permian aged sedimentary rocks. Although the rocks are now thousands of feet above sea level, sediments that form the rock were deposited in the Delaware Basin, which was a shallow marine coastal setting at the southern edge of what was then the North American craton. Sediments were deposited in an environment that is thought to be similar to present day environments in the Bahamas or southern Florida (U.S.), where warm climate and clear water is a favorable environment for photosynthetic organisms and formation of carbonate reefs. As the organisms die and are buried, calcium carbonate incorporated from sea water into shells forms Limestone rock, preserving fossils and their ecology in the rock record. Carbonate production in the Delaware Basin formed the Capitan Reef, one of the most extensive and continuous prehistoric limestone reefs now exposed at the land surface. Buried organic matter formed oil and natural gas resources, and ~250,000 wells have been drilled in the surrounding region. Bedrock that formed in shallow oceans of the Delaware Basin were likely uplifted during the Cenozoic period. Subduction of the Farrallon plate underneath the Western United States thickened buoyant continental crust and uplifted the Colorado Plateau across much of the southwestern United States. Following complete subduction of the Farrallon plate in the mid-late Cenozoic, lateral compression was released along the western margin of the North American tectonic plate, and a