Exploring Ice Caves

This article was originally published in The Midden – Great Basin National Park: Vol. 24, No. 2, Winter 2024.

Checking out the ice at the bottom of Deep Fall Cave

Jean Krejca

By Gretchen Baker, Ecologist & Cave Specialist and Doug Powell, Retired Geologist, USFS

Great Basin National Park is in the state of Nevada. Have you ever thought about what “Nevada” means? In Spanish it means snowy. Generally, when people think of Nevada, they think of Las Vegas and of lots of hot, dry desert, not snow. However, Nevada does have some high elevation that accumulates major snowpacks every year. The Sierra Nevada might be the place that comes immediately to mind, but on the far side of the state, Great Basin National Park is another snowy place. It hosts the state’s second highest peak, Wheeler Peak, at about 13,063 feet, and is also home to about 40 caves.

Lehman Caves is the best known of the caves and you can drive almost right to the entrance at 2,070 meters (6,800 feet) elevation. It is a comfortable 10 degrees Celsius (50 degrees Fahrenheit), however, the Park has three caves that are at a much higher elevation and are so cold that they contain perennial ice. Over the past few years, various efforts have been made by the park staff, volunteers, and funded projects to map, inventory, and monitor these caves.

Park staff measuring ice in Long Cold Cave.

Jean Krejca

Long Cold Cave is about an hour leisurely hike from camp with stunning views. The cave is about 120 meters (390 ft) deep and except for a couple of short horizontal stages, the cave is mostly vertical, traversing down from rebelay to rebelay. At the bottom of the first 40-meter entrance drop, major changes are seen each year, presumably due to the spring thaw. Though, as you traverse down through the cave, major changes (loss) in the amount of ice is very evident over the last few years. Only ten years ago, we rigged most of Long Cold Cave with ice screw anchors and rebelays to descend to the bottom. Now, most of that ice has disappeared or gotten so thin that we have to depend on bolted anchors. The bottom of the cave is very frozen from seasonal melting ice from above and changes are seen from year to year. Some years there have been pools of water accumulated in the bottom room.

Hiking to one of the ice caves in Great Basin National Park

NPS Photo/G. Baker

Deep Fall Cave is about a three-hour hike from camp, over a mountain and along a cliffside following bighorn sheep trails. The cave is over 40 meters (120 ft) deep. After traversing a big snow pile at the entrance and descending the first pitch on to a snow floor, the snow transitions to ice in the Great Room. Just below that is a layered ice fall, which also contained pine needles and woodrat scat. Then the cave descends to the final room, where a giant ice pillar dominates the space. This ice pillar varies in height and width depending if the floor around it is frozen solid or slushy.

The Park is monitoring temperature and humidity in these caves using HOBO ProV2 dataloggers. They are programmed to record every one to two hours over the course of several years. The dataloggers are located at different levels of the cave so that we can monitor how the temperature and humidity change from the entrance, through the twilight zone, and down deep in the cave.

One thing that has become clear is that these caves have temperatures that are quickly warming to 0 degrees Celsius (32 degrees Fahrenheit). Why does a slight temperature increase matter? Most of the time it doesn’t, but when the cave has a lot of ice and is nearing the melting temperature, the cave can change dramatically, and we are already seeing it happen.

Getting ready to get an ice sample from a layered area in Deep Fall Cave.

Jean Krejca

In places, the ice has many layers, indicating it was formed over many years. We feel the time crunch to learn what we can about it before it’s gone. In order to do that, the Park has partnered with Dr. Jeff Munroe at Middlebury University, who is one of the foremost experts in the United States in cave ice. He loaned the Park a special drill attachment so we could easily initiate ice sampling. The Park has also partnered with the Department of Geography and Byrd Polar and Climate Research Center at The Ohio State University (OSU) to develop protocols on how to take samples from these very remote sites.

In September, Park and USFS cave specialists along with members of the Great Basin Institute’s Wild Cave Crew spent a week up at elevation. We hiked to the caves, descended on ropes, drilled into the ice to get samples, photo documented the ice, and returned with 10 samples from both Long Cold and Deep Fall Caves.

The ice samples were allowed to melt but kept refrigerated, then sent to OSU, where students and professors are doing various tests using isotopes, major ions, and microbiology to learn more. We hope to highlight some of the results in a future article.

These caves are not the easiest places to get, but we hope the ice they hold can tell us more about past climate conditions. Sometimes you just have to go to great depths to find out what’s going on.