Dendroglaciological evidence for Holocene glacial advances in the Todd Icefield area, northern British Columbia Coast Mountains

Accelerated glacial recession and downwasting in Pacific North America is exposing land surfaces and features buried by glacial advances that, in many locations, predate the recent Little Ice Age (LIA). Dendrochronologic analyses of increment core samples from living trees (Abies lasiocarpa, Tsuga mertensiana) and samples of subfossil wood collected in the Todd Icefield area, Boundary Ranges, British Columbia Coast Mountains, provide the basis for a dendroglaciological and radiocarbon-based reconstruction of late Holocene glacier activity. Five intervals of glacier expansion were recorded by trees killed or buried by advancing glaciers: (1) an advance prior to similar to 3000 C-14 years BP; (2) an advance at similar to 3000 C-14 years BP that coincides with the regional Tiedemann advance; (3) an unattributed advance at 2300 C-14 years BP; (4) a two-phase advance at similar to 1700 and similar to 1450 C-14 years BP that corresponds with the regional First Millennium advance; (5) an advance with three phases of expansion that began prior to similar to 750 C-14 BP and is consistent with the regional early LIA interval and a two-phase interval of late LIA expansion culminating after similar to 240 and 100 years BP. This chronology of late Holocene glaciation matches that emerging from similar investigations in the coastal cordillera of Pacific North America and provides additional support for the regional significance of both the Tiedemann and the First Millennium advances.