Great Basin National Park's Ice Caves

By Gretchen Baker, Ecologist and Cave Specialist, Great Basin National Park, and Doug Powell, retired geologist, U.S. Forest Service. First published in The Midden*, Vol. 24, No. 2, Winter 2024.*

Snowy Nevada

"Nevada" means snowy in Spanish — hard to square with Las Vegas and hot desert. But the state has high mountains with deep snowpacks: the Sierra Nevada, and on the far side of the state, Great Basin National Park, with Wheeler Peak (about 13,063 feet, Nevada's second highest) and about 40 caves.

Lehman Caves, the best known, sits at 2,070 meters (6,800 feet), a comfortable 10°C (50°F). But three higher caves are cold enough to hold perennial ice, and park staff, volunteers and funded projects have been mapping, inventorying and monitoring them.

Hiking to one of the ice caves. NPS photo / G. Baker.

Long Cold Cave

• Getting there: about an hour's easy hike from camp, with stunning views.
• The cave: about 120 meters (390 feet) deep, nearly all vertical, descended on ropes from anchor to anchor.
• Change: the bottom of the first 40-meter drop changes every year, probably with the spring thaw. Deeper down, ice loss is obvious: ten years ago most of the cave was rigged with ice screws; now that ice is gone or too thin, and cavers rely on bolts. The bottom stays frozen from meltwater refreezing, and some years pools form.

Deep Fall Cave

• Getting there: about three hours, over a mountain and along cliffs on bighorn sheep trails.
• The cave: over 40 meters deep. A big snow pile at the entrance gives way to snow, then ice, in the Great Room; below is a layered icefall holding pine needles and woodrat droppings, and in the final room a giant ice pillar that grows and shrinks as the floor freezes or turns to slush.

Warming toward melting

HOBO data loggers at several levels — entrance, twilight zone and deep inside — record temperature and humidity every one to two hours for years. They show these caves warming quickly toward 0°C (32°F). A small rise usually doesn't matter, but when a cave is full of ice at the melting point, it can change dramatically — and it already is.

Racing to sample the ice

The ice is layered, built up over many years — a record of past climate that may soon be gone.

• Dr. Jeff Munroe of Middlebury, a leading U.S. expert on cave ice, lent the park a drill attachment for sampling.
• Ohio State University's Department of Geography and Byrd Polar and Climate Research Center helped design sampling protocols for such remote sites.
• September: park and Forest Service cave specialists and the Great Basin Institute's Wild Cave Crew spent a week at elevation, rappelling into the caves, drilling and photographing the ice, and bringing back 10 samples from Long Cold and Deep Fall.
• The samples were melted, kept cold, and sent to Ohio State for isotope, major-ion and microbiology tests; results were to come in a later article.

These caves aren't easy to reach, but their ice may tell us much about past climate. Sometimes you have to go to great depths to find out what's going on.

Sources

Based on "Exploring Ice Caves," by Gretchen Baker and Doug Powell, The Midden — Great Basin National Park, Vol. 24, No. 2, Winter 2024, National Park Service; a work of the United States government in the public domain. Three photographs credited to Jean Krejca are not reproduced. The source gives Deep Fall's depth as "over 40 meters (120 ft)," two figures that do not quite match, and calls Munroe's institution "Middlebury University"; it is Middlebury College.