Carlsbad Caverns National Park is a U.S. National Park in the Guadalupe Mountains in southeastern New Mexico. The main attraction within the park is Carlsbad Cavern. This show cave includes a large cave chamber, the Big Room, a natural linestone chamber that is nearly 4,000 feet long, 625 feet wide and 255 feet high at the highest point. Carlsbad Cavern is the fifth largest chamber in North America and the twenty-eighth largest in the world.
It is estimated that around 250 million years ago, the area surrounding Carlsbad Caverns National Park served as the coastline for an inland sea. Within this sea was diverse marine life, whose remains formed the reef. Unlike modern reef growths, this reef contained bryozoans, sponges and other microorganisms. Eventually, most of the water evaporated and the reef was buried by evaporites and other sediments. Tectonic movement then occurred, uplighting the reef above ground followed by erosion and water sculpting the Guadalupe Mountain region into its present-day state.
You can learn more about the park here.