LOST LANDSCAPES: A PALEOGEOGRAPHIC RECONSTRUCTION OF THE QUEEN CHARLOTTE ISLANDS ARCHIPELAGO, WESTERN CANADA 8.7 TO 14.2 KA BP

The Americas’ first humans are thought to have migrated down the west coast of North America subsequent to the last glacial maximum (LGM). However no evidence dating prior to 10.3 ka BP has yet been found along the British Columbia (BC) mainland - Alaska coast. Is this a consequence of a lack of early archaeological sites, or is it because coastlines have shifted making site identification difficult.

A series of paleogeographic maps and isostatic crustal displacement maps chart the sequence of evolving landscapes and display temporal changes in the magnitudes and extent of crustal flexure which resulted in a lack of uniformity in relative sea levels across the Queen Charlotte Islands (QCI) region. These maps were derived from the integration of the following data sets: habitat characteristics and age of molluscs collected from submarine cores, submarine grab samples, and raised beaches; sedimentological analysis of cores and raised beaches; seismic reflection and sidescan sonar records; and bathymetry.

An estimated 690 m of glacial ice began retreating from Dixon Entrance after 14.5 ka BP and prior to 12.6 ka BP, permitting over 100 m of uplift in northern Hecate Strait. A forebulge persisted in Hecate Strait and QC Sound from 13.2 until after 9.7 ka BP implying fixed glacial ice on the BC mainland until ~10 ka BP. Paleogeographic reconstructions show two emergent ice-free terrains extending across the continental shelf (100-150 km) that could have been inhabited by plants and animals, including coastally migrating early humans. Ice-free terrain, present by 13.7 ka BP, were intermittently connected via a landbridge to the Queen Charlotte Islands and the BC mainland. Edible molluscan resources were available from at least 13.2 ka BP. Malacological evidence supports paleoceanographic and palynological studies of a late-glacial Younger Dryas cooling event around the southern limits of Hecate Strait and QC Sound, potentially requiring early peoples to migrate greater distances to collect coastal resources and/or increase their reliance on land-based resources. Early coastlines that have not been drowned and which may harbour early archaeological sites are identified along the western QCI and the BC mainland.