The United States Army maintains and operates a unique research facility near Fairbanks, Alaska, known as the CRREL Permafrost Tunnel. CRREL is short for the U.S. Army's Cold Regions Research and Engineering Laboratory, part of the U.S. Army Corps of Engineers Engineer Research and Development Center. The Permafrost Tunnel was excavated into a man-made escarpment, and is approximately 110 meters in length, 2 to 2.5 meters high, 4 to 5 meters wide...(more)The United States Army maintains and operates a unique research facility near Fairbanks, Alaska, known as the CRREL Permafrost Tunnel. CRREL is short for the U.S. Army's Cold Regions Research and Engineering Laboratory, part of the U.S. Army Corps of Engineers Engineer Research and Development Center. The Permafrost Tunnel was excavated into a man-made escarpment, and is approximately 110 meters in length, 2 to 2.5 meters high, 4 to 5 meters wide, and 15 meters below the surface. The tunnel is composed of two portions: the adit (horizontal passage), which passes entirely through frozen silts, and the winze (inclined adit), which extends off of one side down 45 meters passing through silts, a gravel layer, and then into bedrock. The bottom of the winze is approximately 5 meters lower than the adit. The tunnel's frozen walls expose a continuous cross section of undisturbed, perennially frozen, fossil-rich silt, sand, and gravel on top of bedrock. Also exposed in the tunnel are a variety of ground ice types, including ice wedges, thermokarst cave ice, and ice lenses, each described further in the section. Visible throughout the permafrost are a diverse assemblage of animal fossils and plant remains. Beatles, mites, flies, moths, butterflies, and snail shells are all frozen in time. Bones and teeth of bison, mammoth, and horse are among the vertebrate fossils that are visible. To maintain the frozen condition of the tunnel it is chilled in two ways. In the summer a refrigeration system cools the inside, and in the winter the cold outside ambient air is blown in. Today the CRREL Permafrost Tunnel is an active underground laboratory available for a variety of research programs. Each year, CRREL welcomes many research scientists and engineers interested in conducting research on the processes and properties of frozen soils.
