CHARACTERIZING SNOW AVALANCHES RECORDED IN LAKE SEDIMENTS IN CENTRAL COLORADO

With the increasing impacts of climate change on mountainous regions, especially in the alpine zone, there is a pressing need to understand how climate and climate fluctuations impact the frequency of snow avalanches. Snow avalanches are large and quickly displaced masses of snow moving down steeply sloped terrain. Where areas prone to snow avalanches coincide with boundaries of society, significant economic losses can occur and and loss of life. However, little is known about historic snow avalanche activity and frequency in remote alpine systems. One way to bridge this knowledge gap is through the use of alpine lake sediment as an archive of avalanche events.

This project uses lake sediments from two high elevation lakes in central Colorado to answer the following questions: (1) How are snow-avalanches recorded in the sediments of two subalpine lakes in central Colorado and, (2) What are the relationships between historic snow avalanches, or clastic sediment events, and existing paleoclimate data? A GIS was used to determine which lakes in Colorado were prone to snow avalanches based on their geology, existing past avalanche tracks, slope, and aspect. The lakes have distinct inorganic sediment bands (silt and sand) associated with large plant remains that interrupt the organic clay that characterizes most of the cores. Preliminary laboratory analyses, specifically loss-on-ignition and geochemistry data (XRF), suggest low percent organics and high percent mineral and titanium content during these clastic events. Particle size analysis is forthcoming and results will be discussed in the poster. Upon characterizing the events, and if they are related to snow avalanches or some other geomorphic process, the data will be compared with paleoclimate data from the region to determine if certain climate regimes influence the frequency of events.