CARLSBAD, N.M. (AP) -- It's been more than two decades since a discovery this big has been made at Carlsbad Caverns National Park in southeastern New Mexico.
Park officials announced this week that a new room has been discovered high in the ceiling of the main cavern. It was found on Halloween night by Derek Bristol, a caver and volunteer with the Cave Research Foundation, and Shawn Thomas, a cave technician at the park.
The two had climbed more than 250 feet to the "Spirit World" area to finish surveying as part of work to create a new map of the caverns. Once inside, they decided to make their way to a ledge about 15 feet away. The ledge had been observed on previous trips but never explored.
"Most of the time, obscure leads like this go nowhere," Thomas said.
To their surprise, it opened up to a long passage.
"I remember being really shocked. I couldn't believe this was happening," said Thomas, who followed Bristol through the passage and into the large room they dubbed Halloween Hall. "There hasn't been a room this big discovered in decades."
Inside the colorful room were football-size crystal formations, light-blue endellite clay, a cascade of flow stone left behind by mineral deposits and thousands of bat bones. The room is about 100 feet in diameter.
Bristol and Thomas did not have time to venture beyond the entrance of the room so more exploration and mapping is planned for early next year.
Park spokeswoman Valerie Gohlke told the Carlsbad Current-Argus (http://bit.ly/1bCuD4M) that there's more to be discovered and the recent find should spark interest in new explorations.
Halloween Hall will not be open to the public due to inaccessibility and safety issues. The climb is too difficult for the average climber, Thomas said.
More than 400,000 people visit Carlsbad Caverns each year to get a glimpse of the monumental stalagmites and stalactites, delicate soda straws, translucent draperies and reflective pools that decorate the park's main attraction, the Big Room.
Only a fraction of visitors get a chance to experience off-trail tours because of limited reservations.
Since Carlsbad Caverns' discovery around 1898 by a teenage cowhand, scientists and explorers have discovered more than 118 caves in the area.
The fascination with Carlsbad Caverns comes partly from the way the caves were formed, a process responsible for just 5 percent of the world's caves. It started some 250 million years ago with the creation of a reef formed from the remains of sea sponges and other creatures. Then came evaporation, erosion and uplift. Rainwater seeped down while hydrogen sulfide-rich water migrated upward from the vast oil and natural gas deposits below. The resulting sulfuric acid ate away the limestone, forming the massive chambers that visitors see today.
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