Over millions of years, segments of the Capitan Reef were uplifted, and much of the sediment was eroded away from the more resistant limestone reef materials. The Guadalupe Mountains, stretching to the northeast from El Capitan in Texas to near Carlsbad, New Mexico, are one of these uplifted portions of the reef. The southern end of the range is included within Guadalupe Mountains National Park. As this uplift continued, groundwater that supported some of the material in many of the caverns drained away, and material collapsed to form large underground chambers, such as those in Carlsbad Caverns National Park. Because the reef was built, in large part, through the accumulation of dead marine organisms that incorporated calcium carbonate into their structures, fossils are abundant in the reef deposits throughout the exposed portions of the Guadalupe Mountains.