The Ice Free Corridor has been invoked as a route for Pleistocene human and animal dispersals between eastern Beringia and more southerly areas of North America. Despite the significance of the corridor, there are limited data for when and how this corridor was used. Hypothetical uses of the corridor include: the first expansion of humans from Beringia into the Americas, northward postglacial expansions of fluted point technologies into Beringia, and continued use of the corridor as a contact route between the north and south. Here, we use radiocarbon dates and ancient mitochondrial DNA from late Pleistocene bison fossils to determine the chronology for when the corridor was open and viable for biotic dispersals. The corridor was closed after ∼23,000 until 13,400 calendar years ago (cal y BP), after which we find the first evidence, to our knowledge, that bison used this route to disperse from the south, and by 13,000 y from the north. Our chronology supports a habitable and traversable corridor by at least 13,000 cal y BP, just before the first appearance of Clovis technology in interior North America, and indicates that the corridor would not have been available for significantly earlier southward human dispersal. Following the opening of the corridor, multiple dispersals of human groups between Beringia and interior North America may have continued throughout the latest Pleistocene and early Holocene. Our results highlight the utility of phylogeographic analyses to test hypotheses about paleoecological history and the viability of dispersal routes over time.

ABSTRACT. Since the original 1997 discovery of ancient hunting implements in melting alpine ice patches of southern Yukon, approximately 146 well-preserved, organic artifacts have been recovered. Most of the artifacts, variously made of antler, bone, wood, and stone, represent complete or partial examples of throwing-dart (atlatl) and bow-and-arrow technology. Radiocarbon dates obtained thus far range from 8360 BP to 90 BP (uncalibrated). Our research indicates that in southern Yukon, throwing-dart technology persisted from at least 8360 BP to approximately 1250 BP, when it was abruptly replaced by bow-and-arrow technology. The collection has afforded archaeologists and First Nation researchers a unique opportunity to learn about past hunting technologies and practices and thus greatly improve our understanding of the enduring relationships between humans and caribou.

Since 1997, more than 207 archaeological objects and 1700 faunal remains have been recovered from 43 melting ice patches in the southern Yukon. The artifacts range in age from a 9000-year-old (calendar) dart shaft to a 19th-century musket ball. This paper provides an update on Yukon ice patch research and summary data on select areas of research conducted since 2003. More than 200 radiocarbon dates have been run on ice patch archaeological and faunal materials, and these data allow us to observe and comment on apparent temporal trends. Analysis undertaken since 2003 has improved our understanding of the development and maintenance of hunting technologies, including dart shaft design, wood selection, and point styles. Of particular interest is the description of three different techniques for the construction of throwing darts and the observation of stability in the hunting technology employed in the study area over seven millennia. Radiocarbon chronologies indicate that this period of stability was followed by an abrupt technological replacement of the throwing dart by the bow and arrow after 1200 BP.

ABSTRACT. Since the discovery of dung-rich alpine ice patches in southwest Yukon in 1997, continuing multidisciplinary studies have provided a unique window on the biology, climate, and hunting activity in this region over much of the Holocene. Aerial surveys have identified 72 ice patches of variable size, and 65 patches have been ground-surveyed for organic remains. Of these, 35 yielded an abundance of biological specimens, including caribou and other rare large mammal remains, mummified small mammals and birds, and artifacts spanning 8000 years. The dung provides pollen and plant macrofossils for analysis and paleoenvironmental reconstruction, as well as dietary, genetic, and parasitic information. Stratigraphically controlled sampling of dung within ice layers has yielded a geochronology placing their formation as early as 8300 to 8000 years BP. Ice patch formation was nearly continuous except for an interval between 6700 and 4700 years BP and another between 1440 and 1030, when warm or dry conditions (or both) resulted in no net ice accumulation. Resumption of ice accumulation over the following 500 years likely culminated in the Little Ice Age. The size of the ice patches during this period is made evident by a lichen-free zone that haloes each patch. More recently, interpretation of air photos from 1946 to 2001 has found a significant reduction in ice patch dimensions. Daily temperature records for Whitehorse (1942 -2001) were used to calculate melting degree-day values that account for a large part of the variation in ice patch size, indicating that while considerable melting has likely occurred since the end of the Little Ice Age, the ice patches are highly sensitive to decadal changes in temperature.

ABSTRACT. Discussions of the development of past hunting equipment generally focus on lithic and bone projectile points and foreshafts, as these are often the only elements remaining in archaeological sites. In the last 15 years, the archaeology of alpine ice patches has provided a unique opportunity to analyze hunting equipment over time and gain knowledge of the wooden elements on which the points are hafted. This paper describes the wood and morphometrical analysis of a collection of 27 arrow shafts from two ice patch regions of the western Canadian Subarctic. In both regions, two main categories of arrow shafts show the selection of specific pieces of wood, spruce (Picea sp.) on the one hand and birch (Betula sp.) on the other, with associated morphometrical characteristics. These shafts also share some characteristics that are distinct from those of Arctic and coastal arrow shafts. Shafts of pine (Pinus sp. sec. ponderosa) and hemlock (Tsuga sp.) were also identified in the southwestern Yukon Territory. The absence of correlation between the arrow shaft types and 14 C dating raises the question of the significance of the arrow types and the potential for function, trade, or travel to explain the variation.Key words: archery, arrow shafts, ice patch archaeology, wood analysis, xylology, Subarctic, Arctic, Southwest Yukon, Northwest Territories RÉSUMÉ. Les discussions sur le développement des armes de chasse se concentrent généralement sur les pointes de projectile et les préhampes en matières lithiques et osseuses car ce sont ces éléments qui sont les plus souvent retrouvés dans les sites archéologiques. Ces quinze dernières années, l'archéologie des névés alpins nous donne l'opportunité unique d'analyser des équipements de chasse sur le long terme et de documenter les éléments en bois au bout desquels les pointes sont emmanchées. Dans cet article, nous décrivons l'analyse d'une collection de vingt-sept hampes de flèche en bois végétal provenant de deux régions de névés du Subarctique canadien. Dans les deux régions, on définit deux catégories principales de hampes de flèche qui montrent une sélection spécifique de pièces de bois d'épicéa (Picea sp.) et de bouleau (Betula sp.) auxquelles correspondent des caractéristiques morphométriques propres. Ces hampes partagent aussi des caractéristiques qui les distinguent de celles plus nordiques des côtes de l'Arctique. Des hampes faites en bois de pin (Pinus sp. sec. ponderosa) et de pruche (Tsuga sp.) ont également été identifiées dans le Sud-ouest du Territoire du Yukon. L'absence de corrélation entre les types de hampe de flèche et les dates radiocarbone soulève la question du sens à donner à ces types de flèche. Des facteurs tels que la fonction, les échanges ou des déplacements de personne sont envisagés.