CHARACTERISTICS OF 2 LANDSLIDE-DAMMED LAKES IN A GLACIATED ALPINE ENVIRONMENT

Two young landslide-dammed lakes in a remote portion of Glacier National Park, Montana, were studied to determine if their characteristics are similar to those of older glacial lakes. We sampled lake depth along longitudinal transects and collected lake-bottom sediments for examination of particle size, organic matter content, and presence of benthic vegetation. Water-quality data were also analyzed. The older Slide Lake has a less steep bottom and supports benthic vegetation; the younger Slide Pond, with a steep bottom profile, does not. Organic matter content and sediment textural characteristics were a function of location in each lake, particularly in terms of proximity to each of the landslide dams. Although geomorphically different in terms of origin from glacially scoured lakes, the water-quality characteristics of the landslide-dammed lakes are similar to those of small glacial lakes in the park.