BY CAITLYN FLORENTINE
Alaska. Antarctica. Svalbard. The European Alps. The Andes. These typical glacial settings often bring to mind landscapes characterized by smooth expanses of white, devoid of vegetation, and plentiful in ice.
However, glacial terrain in Southwest Montana – rock-glacier terrain that is – has sharp rocks, abundant evergreens, and a lack of ice. The Beartooth Plateau, the Absaroka, Gallatin, and Madison ranges are home to more than 380 rock glaciers. Lone Mountain (a.k.a. Lone Peak) alone, located within the Madison range, harbors nearly ten of these rock glaciers on its flanks, one of which underlies a considerable area of Big Sky resort terrain. The Lone Peak rock glacier (LPRG) is one mile in length, originating at the base of the Big Couloir and extending all the way beyond the natural half-pipe off of the green run Mr. K on the lower mountain.
How can Southwest Montana, a mid-latitude, cold but relatively dry area, be considered a glacial setting? What is a rock glacier and how can an environment so covered in rocks and trees simultaneously harbor glaciers? Could these “rock glaciers” provide micro-environments suitable for microbial life found in similar glacial environments? In the past two years, since moving to Bozeman in the fall of 2008, I have conducted research on the LPRG: its regional context in Southwest Montana, its internal structure and its role as a microbial habitat.
Glaciers are slow moving rivers of ice. Rock glaciers are slow moving rivers of rock and ice. Scientifically they are described as “talus-mantled geomorphic features that are lobate in shape, bordered by steep margins, and that flow due to the presence of inferred internal ice.” Rock glaciers look like rock tongues or rock streams. They flow down the sides of mountains where rocky material is abundant and ice is present either as a vestige of the past, or a token of the present. Serious debates still remain as to whether rock glaciers are old ice glaciers buried in rock, or if they are piles of rock frozen together by ice sourced in modern precipitation.
MSU professor of Earth Sciences Mark Skidmore has performed research in typical glacial settings around the world — Antarctica, the Alps, and the Yukon Territories – studying subglacial environments as habitats for microorganisms. He looks at the relationship between microbial life and the presence of rocky material in icy environments. Rock glaciers contain both rocky material and ice, so it figures they might serve as happy habitats for microbial life much the same way as subglacial environments do in typical glaciers. However, prior to work Dr. Skidmore and I conducted on the LPRG, rock glaciers have previously never been considered for their microbial component.
Advised by Dr. Skidmore, I performed initial analyses on the microbial and geochemical component of rock glacier ice. Just above the bottom tram station at Big Sky Resort, I excavated ~9 ft of rock glacier debris with the mechanical assistance of a mini-bobcat excavator. This excavation revealed a continuous ice surface, which I sampled via a chain-sawing technique. I took the ice samples back to MSU to be considered for microbiology and geochemistry.
Big Sky Institute graduate Fellow and Montana State University (MSU) graduate student Caitlyn Florentine is from Louisville, Colorado and has a bachelor’s degree in geology from Colorado College. She currently holds a position at MSU as lab manager with the Paleoecology research group. She is also a part-time snowboard instructor at Big Sky Resort Snowsports School, and is working on preparing chapters of her thesis for publication. You can contact her at email@example.com.