In 1997, sheep hunters in the southern Yukon discovered a 4,300 year old dart in caribou dung in a patch of melted ice. As the site was investigated, it was found that annual snow and caribou dung were deposited in layers that also contained numerous artifacts and the mummified remains of birds and small mammals. Caribou used ice patches to seek relief from heat and insects, and ancient hunters observed this behaviour, using it to their advantage. Greg Hare, the Yukon archaeologist who examined the 1997 finds reported that "We recovered more than 200 ancient hunting artifacts, with the oldest dating back more than 9,000 years." Ice patch archaeology was born.
     These early ice patch discoveries led archaeologist Tom Andrews of the Prince of Wales Northern Heritage Centre in Yellowknife in the Canadian Northern Territories, leader of the International Polar Year Ice Patch Study, to wonder if the same phenomenon could be found in the Mackenzie Mountains. In 2000, he raised enough funds to purchase satellite imagery of particular areas of the mountain range, which forms the border between the Yukon and the Northwest Territories, and begin to study the ice patches. This was followed up in 2005 by a four-hour helicopter ride to further investigate two of the patches. This initial trip was a success - "Lo and behold, we found a willow bow," said Andrews. Early success meant federal funding was forthcoming, giving Andrews and his team, which includes indigenous Shutaot'ine (Mountain Dene) experienced in local lore and guiding, the opportunity to explore eight ice patches over four years.
     "We're just like children opening Christmas presents. I kind of pinch myself," said Andrews. Finds include spear throwing tools from 2,400 years ago, a 1000 year-old ground squirrel snare, and 850 year-old bows and arrows. "The implements are truly amazing," he states, "There are wooden arrows and darts so fine you can't believe someone sat down with a stone tool and made them... We are talking of complete examples of ancient technology, including arrows with wooden shafts, feathers and sinew hafting. These artifacts are giving us an entirely new appreciation of how ancient hunting tools were made and used."  
     Radiocarbon dating of the dung shows that the ice patches have been used by caribou for some 6,000 years. Biologists are now studying plant, insect and pollen remains to learn about caribou diet, as well as analysing their ancient DNA to reveal more about population genetics and migration patterns. The evidence can also be used to learn more about environmental changes over time.
     Greg Hare notes the importance of Andrews' 'exceptional' work, which demonstrates that ice patch archaeology is not restricted to a single area, but has "Implications for alpine research around the world. Wherever there is snow cover, archaeologists should at least be considering the possibility of artifact recovery."
     However, while Andrews' and his team hope to monitor some 20 ice patches over the coming years, they have now run out of funding, and two of the eight ice patches originally investigated have already disappeared. He states that 'the ice patches are continuing to melt, and we have an ethical obligation to collect these artifacts as they are exposed. "If left exposed, the artifacts will dissolve in the acidic soils or be trampled by caribou, and in a year or two would be lost forever. The story of this race against time is told in the book 'Hunters of the Alpine Ice."

Sources: Eurekalert, MSNBC (26 April 2010), Discovery News, The Straits Times (28 April 2010)