Late Pleistocene coastal paleogeography of the Queen Charlotte Islands, British Columbia, Canada, and its implications for terrestrial biogeography and early postglacial human occupation

Abstract

Molluscs, sediment lithology, and published sub-bottom profiles are used to deduce sea levels, outline the influence of glacially induced crustal displacement, and reconstruct the paleoenvironment of the northeast Pacific late Quaternary coastline. Geo-spatial modelling shows subaerially exposed land that could have been inhabited by plants and animals, and also coastally migrating early North American peoples. Ice-free terrain, present by at least 13 790 ± 150 14 C years BP, a land bridge, and edible molluscs are identified. Queen Charlotte Islands (QCI) late Pleistocene coastal paleogeography may assist in explaining the biogeography of many terrestrial plant and animal species along the broader northeastern Pacific margin and provide evidence for researchers seeking late Pleistocene -early Holocene glacial refugia. Late Pleistocene -early Holocene coastlines that are not drowned and that may harbour early archaeological sites are identified along the western QCI, where migrants probably first travelled and the westernmost British Columbia mainland, where the effects of glacial ice were reduced.Résumé : Des mollusques, la lithologie des sédiments et des profils publiés du sous-sol du fond sont utilisés pour déduire les niveaux de la mer, définir l'influence des déplacements de la croûte causés par la glace et reconstruire le paléoenvironnement de la côte nord-est du Pacifique au Quaternaire tardif. Des modèles géospaciaux montrent des terres subaériennes exposées qui auraient pu être habitées par des plantes et des animaux ainsi que par des peuples nord-américains primitifs qui migraient sur la côte. Des terrains libres de glace, présents depuis au moins 13 790 ± 150 14 C années avant notre ère, un pont terrestre et des mollusques comestibles sont identifiés. La paléogéographie de la côte des îles de la Reine Charlotte au Pléistocène tardif peut aider à expliquer la biogéographie de plusieurs espèces de plantes et d'animaux terrestres le long de la marge étendue du Pacifique nord-est et fournir des évidences pour les chercheurs qui recherchent des refuges glaciaires au Pléistocène tardif -Holocène précoce. Les côtes du Pléistocène tardif -Holocène précoce qui ne sont pas inondées et qui pourraient contenir des sites archéologiques anciens sont identifiés le long des îles de la Reine Charlotte occidentales, vers lesquelles des peuples migrateurs ont probablement tout d'abord voyagé, et sur la partie continentale la plus à l'ouest de la Colombie-Britannique, où les effets de la glace de l'ère glaciaire étaient moindres.[Traduit par la Rédaction] Hetherington et al. 1766

Late Wisconsinan Port Eliza Cave deposits and their implications for human coastal migration, Vancouver Island, Canada

“…An initial criticism of the coastal-migration theory is that the majority of the route was barred by the extensive Cordilleran Ice Sheet, which advanced to the shelf edge (Prest, 1969). However, this study and recent work (Blaise et al, 1990;Mann and Peteet, 1994;Heaton et al, 1996;Josenhans et al, 1997;Barrie and Conway, 1999;Fedje and Josenhans, 2000;Hetherington et al, 2003;Ward et al 2003;Hetherington et al, 2004) indicate that the LGM was less extensive and diachronous along the coast, allowing the possibility of human migration.…”

The Leech <em>Haemopis lateromaculata</em> (Hirudinea: Haemopidae): Its North America Distribution and Additional Notes on Species Description

“…The Pleistocene-Holocene environments were changing due to eustasy (the sea level rising at least 120 m) and glacio-isostatic surface adjustments involving the advance and recession of the glaciers. Hetherington et al (2003Hetherington et al ( , 2004 mapped this environment for the Haida Gwaii and described a land bridge between the islands and the British Columbia mainland that existed between 11 700 and 11 200 years ago as a result of the presence of a forebulge from the retreating cordilleran glacier. This process, if applied throughout the glaciated region of coastal Alaska, may have allowed island by island transfer of leeches from coastal Pleistocene refugia, thus accounting for the modern day presence of H. lateromaculata populations on the coastal northwestern North America mainland (Reimchen and Byun 2005).…”

The Role of Temperature in the Distribution of the Glacier Ice Worm,Mesenchytraeus solifugus(Annelida: Oligochaeta: Enchytraeidae)

“…Why worms did not disperse inland during the end of the ice age could be due to the rapid violence of retreating tidewater glaciers (Meier and Post, 1987) within the archipelago's fjordlands, leaving ice worms on isolated alpine glaciers. We speculate that the high, cold, and dry Cordilleran Ice Sheet, together with glacial refugia formed by the Hecate Straight forebulge (Hetherington et al, 2003), presented a barrier to northward, active dispersal of the Southern clade. Individuals of the Central clade could have actively dispersed 150 km southward along a coastal route.…”