Earth Notes: Rock Glaciers

Most people think of a glacier as a large white mass of snow and ice. Yet some glaciers actually form beneath debris. These are known as rock glaciers. Surprisingly Colorado is home to more than thirty-five hundred rock glaciers where ice is buried under rock and sand near steep mountain slopes. In fact, this type greatly outnumbers ice glaciers in Colorado, and likely contain a larger volume of ice too.

Many regular ice glaciers are disappearing as Alpine environments are undergoing warming at almost twice the global average. Both the Sierra Nevada and Rocky Mountain ranges contain some of the last ice in the form of rock glaciers. The ice can be buried beneath 10 feet of rock, blanketed from temperature increases and thus less susceptible to melting as the global climate warms. So, rock glaciers provide a refuge to Alpine species reliant on the colder environment.

Researchers at the University of Arizona are studying the viability of such resources as the climate continues to change. They’ve developed a new method to determine the thickness of ice in rock glaciers, as well as the ratio of ice to debris. This allows scientists to attain a more precise understanding of water resources locked in ice on Earth— or on Mars, where rock glaciers are also found.