Sediment depth was measured at several sites within each of eight beaver ponds in Glacier National Park, Montana, and sediment samples were collected from five of these ponds. Accumulation rates of sediments far exceeded published rates from boreal forest landscapes in eastern and central North America. Pond area strongly predicts volume of sedimentation. Textural differences illustrated spatial variations associated with position in a pond and along a pond sequence. Organic matter content was significantly higher in older ponds, and has ramifications for the development of the benthos and the long-term storage of matter in ponds. The role of beavers as biogeomorphic agents is profound, but requires further elucidation to distinguish between fluvial sediment deposition in ponds and sediment deposition associated with beaver excavational activity.