Carlsbad Caverns National Park

Ordinary groundwater did not hollow these caves. Unlike most limestone caves, which carbonic acid dissolves, the caverns of the Guadalupe Mountains were eaten out from below by sulfuric acid, and the gypsum and sulfur left in them are the evidence. The process made more than a hundred caves in the park. The longest is not Carlsbad Cavern but Lechuguilla, a small guano pit until cavers dug through in May 1986; it now runs more than 145 miles and 1,604 feet deep, though no room in it matches the Big Room.

What the plaque says

Official Scenic Historic Marker Carlsbad Caverns National Park These vast and magnificent caverns contain over 21 miles of explored corridors. The chambers contain countless stalactites and stalagmites unrivaled in size and beauty. The caverns are within a reef that formed in an ancient sea 240 million years ago. Millions of years later, the reef was fractured, allowing ground water to begin work fashioning the caverns.

Where it stands

Worth the stop nearby

• Carlsbad Caverns National Park — 4.2 mi
  The way into the cave has changed four times: a guano miner's bucket, a wooden staircase, a 750-foot elevator, and now a timed ticket and a switchback trail down the natural entrance.
• Living Desert Zoo and Gardens State Park — 20 mi
  A zoo and garden of the Chihuahuan Desert on the Ocotillo Hills above Carlsbad, whose animals are injured or orphaned wildlife that cannot go back to the wild.

More markers nearby

• Carlsbad Caverns National Park — 5.5 mi
• Guadalupe Mountains — 8.2 mi
• Goodnight-Loving Trail — 17 mi
• Espejo's Trail — 18 mi