GLACIAL ARCHEOLOGY: A NEW RESEARCH FRONTIER
Dixon, E. James 1 ; Manley, William F. 2 ; Lee, Craig M. 3
1 INSTAAR, University of Colorado at Boulder
2 INSTAAR, University of Colorado at Boulder
3 INSTAAR, University of Colorado at Boulder
Approximately 10% of the earth’s land surface is covered by ice. Global warming is rapidly melting ice and exposing rare archeological remains. These sites are important to understanding the role of high latitude and high altitude environments in human adaptation and cultural development. GIS modeling is being used to identify areas exhibiting high potential for the preservation and discovery of frozen archeological remains. Areas holding the highest potential for archeological site discovery are: 1) ice-covered passes used as transportation corridors, and 2) glaciers and areas of persistent snow cover used by animals that attracted human predators. The primary goals of this research are to first predict site potential throughout Alaska’s Wrangell St. Elias National Park and Preserve, and then to make the model applicable to other glaciated regions of Beringia and other high altitude and high latitude environments.
In 2001 and 2003 numerous archaeological and/or paleontological sites were discovered on melting glaciers and perennial snow patches (aniuvat in Inuit, Kusugak 2002:vi). Historic artifacts included horse hoof rinds and horseshoe nails, cans, tools, historic debris, and even the remains of an entire building. Historic artifacts are most commonly discovered below the equilibrium line altitudes (ELA’s) of large valley glaciers at an elevation of approximately 3400’ (~1036m) that were used as trails and passes over mountain ranges. Prehistoric artifacts include antler projectile points, wooden arrow and atl atl shafts, a birch bark container, and an atl atl foreshaft with a hafted stone projectile point. Prehistoric artifacts are commonly associated with caribou and sheep hunting on snow patches, or aniuvat (c. 2000m), and cirque glaciers (c. 2000m). Elevation, aspect, slope, and vegetation may be used to identify “fossil” snow patches. Numerous paleontological specimens including mammalian hair and fecal material, the remains of sheep, caribou, carnivores, and other medium sized mammals, rodents, birds, and fish, have been discovered.
Glaciers and perennial ice patches most probably used by humans in the past can be detected using GIS modeling using three types of data layers, or coverages: 1) social/cultural, 2) biological, and 3) physical. The areas of highest archeological potential were presumed to be those geographic locals where the three data sets overlapped spatially. Influential layers included biologic and geologic factors such as mineral licks, lithic sources, transportation corridors, and large mammal species ranges caribou, sheep, goats, moose and bears. The social/cultural coverages were compiled from historic, ethnographic and archival sources as well as through interviews with knowledgeable individuals. In addition to historically documented trails, proximity and accessibility to known archeological and historic sites are important variables. Large mammal species distribution data were developed through analysis of the biological literature, studies conducted by the Alaska Department of Fish and Game and the National Park Service, and informant interviews. The physical data layers are derived from the geologic literature, low level color aerial photography, satellite imagery, USGS maps and open file reports, and in consultation with knowledgeable researchers and resource managers. When used in conjunction with data on elevation, aspect, and slope, the statistical analysis of hyperspectral imagery and thermal bands are important variables for predicting potential site locales on relatively small perennial snow and ice patches. These data layers, along with factor proximity weighting using exponential decay with distance from ice and multiple regression analyses, are used to further analyze and predict potential site locales. Field survey is then used to test and refine the site potential model.
Globally averaged mass balance measurements derived from glaciers with 20-year, or longer, records demonstrate that net glacier melting is increasing globally (Dyurgerov 2001:281). Global warming presents an unprecedented opportunity to identify glaciers, ice fields and similar environments that hold high potential for the exposure and discovery of frozen archeological remains. This is an exciting new archeological frontier from which rare, unique and important artifacts made from organic materials are being discovered across the globe. These discoveries provide new insights relating to high altitude and high latitude adaptations to human colonization. Global warming has created an urgent need to develop scientific methods to locate and preserve frozen organic remains because these depositional environments are ephemeral. Exposed organic materials soon decompose or are destroyed.
Acknowledgements: The National Science Foundation, Office of Polar Programs, Social Sciences Division funded this research (OPP-0097753 and OPP-0222490). It was conducted under permits issued by the Alaska Regional Office of the National Park Service and Wrangell St. Elias National Park and Preserve, and with the cooperation of Tad Kehl and Ruth Ann Warden of Ahtna, Inc. VECO Polar Resources provided logistic support.
Dyurgerov, M.B., 2001, Mountain Glaciers at the End of the Twentieth Century: Global Analysis in Relation to Climate and Water Cycle. Polar Geography. 24(4):241-336.
Fig 1. Map illustrating the location of Alaska’s Wrangell-St. Elias National Park and Preserve.
Fig 2. Artifacts discovered on ice patches in Alaska’s Wrangell-St. Elias National Park and Preserve include this stone projectile point which still retains traces of red ochre and the sinew used to lash it to a wooden shaft.