Carlsbad Caverns National Park preserves a portion of the Capitan Reef-one of the best-preserved, exposed Permian-age fossil reefs in the world. Water, geologic forces, climactic changes, and vast spans of time have produced and changed the fossil reef and its spectacular caves, a process that continues to the present day. The ocean fossils here reveal a detailed picture of life along a coastline of a shallow inland sea some million years ago.
These fossils show that the "Capitan Reef" was built mostly of sponges and algae, not by coral like many of today's reefs. Other marine fossils found here include ammonites, crinoids, snails, nautiloids, bivalves, brachiopods, and the occasional trilobite. This coastline eventually became a horseshoe-shaped limestone layer of rock over 1, feet m thick, two to three miles three to five meters wide and over hundred miles km long.
By the end of the Permian age, the Capitan Reef was covered by thousands of feet of newer sediments, burying the reef for tens of millions of years. Local faulting and stresses of the earth's crust, especially over the past 20 million years, has uplifted these reef sediments almost ten thousand feet. Wind, rain, snow and time eroded away the overlying younger sediments and now the ancient reef is exposed once again. The park's deep canyons and caves now provide visitors with unique opportunities to view this fossil reef from the inside.
There are more than known caves within the park alone-they are some of the biggest and longest caves in the world. All of them reveal a very unusual ingredient in cave dissolution creation βsulfuric acid.
Most of the world's limestone caves are created when surface water flows down through cracks in limestone rock and slowly enlarges the passageways. In all surface water, there is a weak acid called carbonic acid.
