The Lonely Life of Idaho's Only Glacier

Idaho’s tallest peak, Mt Borah, the location of the state’s only glacier. PHOTO COURTESY OF COLLIN SLOAN

Four and a half decades after its discovery, the Borah Glacier was officially recognized, named, and put on maps. Now researchers and glacier enthusiasts are curious if it’s really a glacier, and whether Idaho’s mountains are hiding any more.

BY MICAH DREW

Down from the north side of Idaho’s tallest mountain lies an unassuming pile of rubble.

Nestled against the north-facing cirque of Mount Borah, a perennially-present snow field angles downhill into a stretch of boulders and rocks that stretches nearly 2,000 feet downslope to a moraine, a pile of rocks pushed into place by an ancient glacier.

This patch of snow, and more specifically, the seemingly run-ofthe-mill rock pile are covering up Idaho’s most unique geological feature, officially recognized by the U.S. Geological Survey in 2021 as the state’s only glacier.

Collin Sloan exploring a crevasse in the Borah Glacier.

PHOTO COURTESY OF COLLIN SLOAN

DISCOVERY

In the 1970s, a geology student at Boise State University needed a project for Monte Wilson’s geomorphology class. The student, Bruce Otto, was an avid backpacker and decided to do some field work in the Lost River Range to study snowfields on Mount Borah.

“I had a lot of undergraduate naivety,” Otto said. “I was just going to measure this snowfield and see how much it would need to grow in order to be considered a glacier.”

Bruce Otto climbs on the Borah Glacier during a research trip in 1975.

PHOTO COURTESY OF BRUCE OTTO

In 1974, Otto and his father hiked into the cirque, headed for the snow field, and began surveying the site. While walking along the lateral moraine that formed the side of the cirque, Otto stumbled across some crevasses that were “so deep they were black.”

Under the top two or three feet of rock was sheer ice. The entire basin was covering up a mass of ice so thick that it was able to move and flow of its own accord. Otto had discovered the first glacier in Idaho. “Monte was flabbergasted,” Otto said.

A crevasse naturally cut deep into the Borah Glacier. “This was the discovery outcrop that made me think, Holy S*** this is a glacier,” Otto said.”

PHOTO COURTESY OF BRUCE OTTO

That fall, Otto, Wilson, and several students returned to the glacier. They went spelunking in the vast crevasse at the head of the glacier, called a bergschrund, and conducted seismic testing to determine the depth of the ice. The readings showed that the glacial ice, hidden from view by a boulder field, was 210 feet thick in the middle. It stretched 300 meters across and nearly 400 meters in length. Otto estimated the glacier was at its peak in the mid-1800s before the climate began warming.

For the next decade, Otto and Wilson returned to the glacier almost every year, monitoring precipitation in the cirque and taking regular measurements, until 1985 when the monitoring gauge was taken out by an avalanche. They made one attempt to get it registered and named, but didn’t make it through the bureaucratic process.

A Boise State student wedges himself into a crevasse on the Borah Glacier during a research trip led by Bruce Otto.

PHOTO COURTESY OF BRUCE OTTO

“We knew there were potential places for more of them, but we never did any other searching for glaciers,” Otto said. He soon moved from Idaho and went about a career in mineral exploration.

In 2008, an article in the Idaho Statesman quoted a Boise State geology professor saying that the glacier was gone and nothing remained on Mount Borah but patches of snow.

WHAT IS A GLACIER?

The idea of a glacier conjures up enormous rivers of ice, slowly flowing downhill, breaking off icebergs into coastal waters or inland alpine lakes. While those glaciers fit the storybook idea, the definition encompasses a range of hydrogeological features on a much smaller scale.

The United States Geological Survey (USGS) defines a glacier as a “a large, perennial accumulation of crystalline ice, snow, rock, sediment, and often liquid water that originates on land and moves down slope under the influence of its own weight and gravity.”

Glacial researchers classify the features based on their location, nearby landforms, size and internal structure, including debris content. In a traditional classification system, smaller alpine glaciers can be considered “uncovered,” a traditionally white glacier with clearly visible ice; a debris-covered glacier, where the surface is covered by rocks and mud of varying thickness and coverage; and rock glaciers, where the internal structure is a mixture of rock and ice.

Glenn Thackray, a geosciences professor at Idaho State University who studies the history of glaciers, said it’s easy to get mixed up between true glaciers, rock glaciers, and perennial snow fields.

“We have a lot of rock glaciers in Idaho, masses of broken-up rock in steep mountain areas that have some ice in them and seem to flow like glaciers,” Thackray said. “Perennial snow fields, which we have quite a few in Idaho, can melt and refreeze throughout the year and mimic glaciers, but aren’t truly moving in the same way. True glaciers act, look, and function like a glacier.”

It’s the latter that is so rare in this state. According to Thackray, the most distinguishing features of a true glacier are the presence of glacial ice, which is metamorphosed snow compacted together in clear-to-blue-looking ice crystals and the flow of the glacier, where the ice deforms itself internally, as opposed to just following the flow of gravity.

Climate and geography constitute the main reasons Idaho is not a glacier haven. While many neighboring states—Montana, Wyoming, Washington, and Oregon—are home to multiple glaciers, central Idaho’s dry climate and lower elevations limit the annual snowfall critical to maintaining glaciers year after year.

“When we say there’s probably no glaciers in Idaho, we’re really thinking of that idealized glacier notion,” Thackray said. “But rock glaciers, there’s dozens of those throughout the mountain ranges. We just don’t hear much about them because they just look like a pile of rubble, and we have lots of rubble in Idaho’s mountains.”

REDISCOVERY

Self-identified glacier hunter Collin Sloan got hooked on ice in the early 2000s, after hearing reports that the ancient ones in Glacier National Park were vanishing. Unable to make it to Montana to see them in person, the Boise resident turned to Google Earth to see how the glaciers had changed over the years through historical satellite photos.

“It’s such a cool landform,” Sloan said. “To have an amount of ice of that size where it’s moving and shaping the mountain, it’s like a living creature on the side of the mountain. It’s not just a snowfield sitting there.”

When he read in the Idaho Statesman that Idaho’s only glacier was gone, he wondered whether the disappearance was confirmed, saying he felt “offended people were bad-mouthing” Idaho’s only glacier, seemingly without hard evidence. After reading through Otto’s studies, Sloan reached out to climbers and researchers who frequented the area and might offer information about the glacier’s presence.

He searched the three-dimensional satellite maps of Idaho, spending hours scrolling through archival Google Earth images of Mount Borah. He compared each year’s photos, looking for changes in specific rock locations that might indicate movement, depressions that might be crevasses, and how the snowfield’s size changed with each winter. The longer he spent looking at the images, the more he became convinced that there was more to the rubble field than rocks and rumor.

Finally, he decided to see for himself. With his father and three brothers, he set out to rediscover Otto’s glacier in 2015.

“I have a bit of glacial fever when I get going,” Sloan said. “I’m not a big mountaineer, really a desk jockey mountaineer, but I wanted to stand there and see what was actually going on.”

Sloan said that when he reached the cirque below Borah, it just looked like a pile of gravel.

“I was walking down a little slope and suddenly through the gravel, I saw ice,” Sloan said. “It was just perfectly crystal clear ice and I was still almost 1,000 feet from exposed snow. It was awesome that my hunch was confirmed.”

For a glacier to be recognized and listed on a map, the Idaho Department of Water Resources requires the Forest Service to conduct a survey and map the glacier. Just two weeks after Sloan’s visit, Joshua Keeley, with the Salmon-Challis National Forest, checked it out.

In his published report, Keeley wrote that the feature appeared to be relatively unchanged from Otto’s initial surveys, concluding that “the ice mass is indeed a glacier that continues to move under its own weight.” Measurements estimated that the glacier covered roughly 25 acres and crevasses in the ice reached more than 40 feet deep. Keeley also estimated the glacier showed between 50 and 200 centimeters of movement per year.

Keeley was a former student at ISU, and when Professor Thackray read the glacial report, the news inspired mixed feelings.

“I was excited about it, but still have enough questions that I’m not quite sure about it,” Thackray said. “I’m suspicious it may be a persistent snowfield or maybe it’s covering a rock glacier under the snow, but then again, the survey and research was done well and their conclusion that it’s a glacier is very rational.”

With the Forest Service officially concluding that the Otto Glacier was, in fact, a glacier, Sloan set about getting it officially named and recognized. He submitted paperwork to the U.S. Board of Geographic Names (BGN), the federal entity in charge of naming geological features. Due to BGN rules, features cannot be named after living people, so the Otto Glacier was a no-go. Instead, Sloan opted to use the most prominent feature in the area, and the Borah Glacier received its official name in February 2021.

“My glacier is a little bit thinner now,” Otto said from his Boise home. “But it felt really good to have it recognized as still being there.”

Otto, who is in his late 60s and recently had two hip replacements, doesn’t think he’ll ever make it back to his glacier. Still, he continues to cheer on the efforts of Sloan and readily offers up information.

A Google Earth image showing the extend of the Borah Glacier, marked. The glacial ice is hidden under a layer of sediment.

PHOTO COURTESY OF COLLIN SLOAN

As for the skeptical scientists, Thackray plans to take some students to the Borah Glacier next year to do some onsite data collection, with possible trips to Sloan’s other projects as well.

“While I’m scientifically skeptical about some of the features that are being identified as glaciers, I think it’s great [there are] people who want to go out and search for these things,” Thackray said. “We don’t know where everything is for sure, especially in a state like Idaho. There could be some hidden glaciers out there—no question there could be some others.”

Collin Sloan (at right) and his family on a glacier scouting expedition.

PHOTO COURTESY OF COLLIN SLOAN

“I’d be excited if we really found we have a glacier or two in Idaho,” Thackray added. “Studying glaciers in a place that doesn’t have glaciers isn’t very fun.”

Sloan is continuing his pursuit of other possible glaciers in Idaho.

“I consider this to be Bruce’s glacier,” Sloan said. “He discovered it, I just helped it get named. I want to find my own now. And along the way if I could inspire more people to go find more ice, that would be cool.”

Collin Sloan and one of his brothers check a map during their approach to a potential glacier in the Sawtooth Mountains.

PHOTO COURTESY OF COLLIN SLOAN

He says he’s identified one in the Sawtooth Mountains above Redfish Lake and another in the Pioneer Mountains and has made expeditions to both, with plans to return next summer for more comprehensive surveys.

“That guy’s tenacious,” Otto said. “He’ll find others if they exist, but I don’t think there’s that many left around.”