CARLSBAD — Several large boulders that fell overnight blocked the natural entrance to Carlsbad Caverns National Park, but visitors were still allowed into the popular tourist attraction, officials said.
The park remained open today, with visitors being allowed access into the caverns via elevators.
"The only thing they don't have access to is the natural entrance. Everything else is open," said park spokeswoman Aleta Knight. The natural entrance is about 1 1/4 miles long.
Knight said a park ranger discovered the boulders while making her rounds this morning.
"We've got five good-sized boulders weighing 3 to 5 tons that fell sometime overnight blocking the entrance," Knight said. Several smaller boulders also fell onto the trail.
No one was injured.
A crew from the Waste Isolation Pilot Plant was inspecting the entrance Monday, checking for more loose boulders. WIPP personnel were called to the scene for their geological engineering expertise, Knight said.
"We're not letting anyone in (through the natural entrance), including our own employees, until we're sure it's safe," she said. The boulders will not be removed until officials deem the area safe. Knight said she hopes the inspection, which could take as long as a week, will reveal the cause of the fall. "Hopefully it's just natural wear and tear but we don't know," she said.
At approximately 0845 hours on June 26, 2000, a Park Ranger reported that rocks had fallen in the vicinity of Iceberg Rock and that there was enough material to block the trail to visitors. Supervisory Rangers, Maintenance and Cave Resource Specialists went to the scene and discovered a rockfall of approximately three (3) cubic yards that had fallen on the trail. The trail is sufficiently blocked to prevent passage without assistance, however approximately fifty (50) visitors who were already in the cave were able to pass without difficulty with the assistance of Rangers and Maintenance staff.
The rockfall is on the underside of Iceberg Rock, approximately _ mile in from the Natural Entrance on the self-guided Natural Entrance trail, just above the overlook into the Green Lake Room. The debris field is approximately sixteen (16) feet long and contains five major boulders and several smaller ones. The largest rock is approximately 6 feet tall and weighs approximately 2-3 tons. The trail was immediately closed to visitors at the initial notification, and it will remain closed until a thorough assessment can be made and cleanup completed. We anticipate that the area may be closed for several days, perhaps up to a week and will issue additional briefing statements as conditions change. Visitors will still have access to the Big Room, the Kings Palace Tour and the off-trail caving tours.
Caves are inherently stable environments with relatively constant temperatures and humidity, and only minimal air movement due to temperature differentials with the outside air. Conditions that cause rock fall on the surface, such as erosion or the freeze-thaw cycle, do not occur in caves except near cave entrances. Therefore, rockfall in the interior of caves like Carlsbad Caverns is an extremely rare event. A geologist from the nearby Waste Isolation Pilot Project (WIPP) will be assisting NPS Cave Specialists in investigating the cause of this fall and assessing the area for visitor and employee safety. Their inspection will cover the rest of the cave trails, as well, to insure that no other problems exist. Cleanup will begin and the area will be reopened as soon as the job can be safely completed.
Further briefings will be issued as conditions change. When speaking with visitors about this incident, please stick to the facts as you see them here. If you don't know the answer to a question, ASK someone; DO NOT SPECULATE. Please refer all inquires from the media (newspapers, magazines, TV, radio, etc.) to Management Assistant Aleta Knight, Acting Superintendent Chas Cartwright or a Division Chief.