Lone Mountain’s rock glacier mapped by lasers

By Jessianne Castle EBS CONTRIBUTOR

BOZEMAN – As skiers carve powdery turns down the Big Couloir at Big Sky Resort, the ground beneath them is constantly moving by fractions of an inch. Overall, surveys indicate an ancient glacier on Lone Mountain moves as much as 11 inches each year, and advanced mapping technologies suggest the activity is here to stay, at least for a while.

Last summer, a team of students and professors from Montana State University worked with technicians from Bozeman photonics company Blackmore Sensors and Analytics, Inc., using portable lidar laser scanners to create a digital 3-D model of the Lone Peak Rock Glacier. The MSU research team is comparing this model with decades-worth of survey data to better understand trends in activity.

While researchers are particularly interested in the Lone Peak Rock Glacier, the mountain likely holds at least 10 distinct rock glaciers, though the majority are inactive today. These formations consist of a layer of ice that is protected by a thick blanket of talus. The Lone Mountain glacier is suspected to be 100- to 200-feet thick, with 9 feet of rock covering the surface.

Science writer and geologist, Mary Caperton Morton of Big Sky, said rock glaciers are very common in the Rocky Mountains and that Lone Mountain’s are most likely the remnants of traditional ice glaciers. She said that if you look closely, you can see evidence of the glacial activity. “As it melts, it drags rocks with it,” she said, adding that a rippled pattern can sometimes be seen in the snow or rocks below the Big Couloir.

Colin Shaw, an assistant research professor in MSU’s Department of Earth Sciences, is among the group of researchers studying Lone Mountain and its glaciers. He said initial analysis indicates the active portion of the Lone Peak Rock Glacier is approximately 1.5 miles long, extending from the headwall of the east cirque, where the A-Z Chutes are, down to Upper Morning Glory.

“The rate of flow doesn’t seem to be changing even after 50 years,” he said. “Perhaps the talus protects the ice, insulates it from warming.”

While the glacier doesn’t seem to be melting any faster despite warming temperature trends, it’s losing mass as the ice melts—a defining characteristic of a glacier. However, Shaw said, “Even though we’re losing ice mass, the glacier is still getting longer. It’s stretching.”

The glacier was first studied in the 1970s prior to the establishment of Big Sky Resort and this initial survey helped developers install infrastructure on the moving ground surface.

“The configuration of the Lone Peak Tram is such to allow for the bottom terminal to move,” wrote Big Sky Resort’s vice president of Mountain Operations, Mike Unruh, in a statement sent to EBS. “By installing a tram instead of a gondola and eliminating the need for towers, complications due to this movement were greatly reduced. The tram is surveyed routinely to track its movement, and inspected methodically by Doppelmayr engineers from Europe who are familiar with installations on glaciers.”

An image of a 3-D digital model of the Lone Peak rock glacier, captured using lidar laser technology. IMAGE COURGESY OF BLACKMORE

Researchers also routinely survey the area, often using GPS. Additionally, in 2005, an early iteration of lidar was used in an aerial scan by a doctoral student at MSU, while in 2017, students in MSU’s Geology Field Camp used land-based lidar supplied by the National Science Foundation-funded consortium, UNAVCO, to make initial images.

A technology that has been around for years, lidar has been developed for a number of applications. It relies on a high-speed laser that calculates distances real-time in a similar fashion to radar.

Blackmore’s chief technology operator Stephen Crouch said the scanning process can provide accurate 3-D data and orient technology such as drones. He added that his company is interested in developing lidar as a tool for the Department of Defense and as a sensor for autonomous vehicles.