Caribou on ice patch.

During summer in the Mackenzie Mountains, caribou spend much of their time sitting on high elevation ice patches seeking relief from summer insect swarms and warm afternoon temperatures.  Recent research in the Yukon indicates that this relationship has persisted for millennia and has been recorded in the ice.  Ice patches formed as annual net accumulations of snow were gradually compressed into permanent ice lenses and, in the process, the ancient remains of caribou – bone, antler and primarily dung – were incorporated and preserved within the ice.  Humans have known of this relationship for millennia and have a long history of hunting caribou on ice patches, sometimes losing or discarding their hunting implements in the process.  Currently, with changing climate regimes, melting alpine ice patches in the Yukon are yielding caribou remains and hunting implements, providing a material record spanning the last 8,000 years.  This record includes unique examples of Aboriginal hunting implements with preserved organic parts, a remarkable development for the archaeological record of the Subarctic, where the organic components of artifacts are quickly degraded by acidic soils and archaeologists are left to reconstruct past cultures from stone tools.  The bone, antler, wood, sinew, and feather components of hunting implements are preserved within ice patches, and these complete artifacts have helped neighbouring Yukon archaeologists to redefine our understanding of the invention and use of various hunting technologies, such as the bow and arrow.  Well-preserved biological specimens have also proven invaluable to Yukon biologists for reconstructing past environmental conditions and wildlife population dynamics.  For example, pollen trapped in the dung provides a record of past climate and vegetation, and DNA studies on dung pellets have assisted in reconstructing the genetic histories of caribou herds and long-term changes in herd ranges.  For Yukon archaeologists and biologists, this multidisciplinary approach has resulted in a unique database that informs important questions of human history and caribou behaviour.  Yet, the most critical lesson from the Yukon experience is that new artifacts are melting from the ice patches on an annual basis and that these artifacts, wet, fragile and exposed, require immediate conservation measures to be preserved.

Ice Patch archaeological site showing Glen MacKay examining caribou dung melting from ice margin.

Recent work in the Mackenzie Mountains indicates that this ice patch phenomenon is also present in the Northwest Territories and in need of immediate attention.  We initiated a project in 2002 to locate and assess ice patches in the Mackenzie Mountains.  Working over three years with satellite imagery and aerial photos – in partnership with the NWT Centre for Remote Sensing – we were able to locate areas in the mountains that had visible summer ice patches.  In 2005, working in partnership with Tulita First Nations Band, we conducted a 5-day helicopter survey in the middle Mackenzie Mountains, between Norman Wells and the Yukon border, south to the headwaters of the South Nahanni River, and as far north as the headwaters of the Arctic Red River.  Two new archaeological sites associated with ice patches were recorded during this brief survey.  One of the sites produced wooden artifacts – possibly fragments of a bow made from willow – and the second yielded broken caribou bone with fracture patterns indicative of human butchering practices.  We also collected caribou dung from the second site.  Analysis is still underway and includes radiocarbon dating of the cultural remains and bone.  NWT biologists are leading the analysis of biological specimens from the sites, which include stable isotope analysis, diet composition and DNA analysis.  These analyses will provide information on environmental changes and a comparison of past and present ecology of wildlife in the Mackenzie Mountains.  This archaeological and biological work will lead to unique insights into the human and ecological history of the Mackenzie Mountains and will also extend the geographical range of the ice patch work in the Yukon, providing a broader regional scope to these studies.