Quaternary stratigraphy and glacial history of the Peace River valley, northeast British ColumbiaThis article is one of a selection of papers published in this Special Issue on the theme Geology of northeastern British Columbia and northwestern Alberta: diamonds, shallow gas, gravel, and glaciers.

Abstract

Two Cordilleran and three Laurentide glacial advances are recorded in Quaternary sediments and landforms in the Peace River valley, northeast British Columbia. The advances are inferred from fluvial gravels, glaciolacustrine sediments, and tills within nested paleovalleys excavated during three interglaciations and from the distribution of granitoid clasts derived from the Canadian Shield. Till of the last (Late Wisconsinan) Laurentide glaciation occurs at the surface, except where it is overlain by postglacial sediments. The advance that deposited this till was the most extensive in the study area, and the only advance definitively recognized in western Alberta south of the study area. Late Wisconsinan Cordilleran till has not been found in the study area, but Cordilleran and Laurentide ice may have coalesced briefly during the last glaciation. Support for this supposition is provided by the inferred deflection of Laurentide flutings to the southeast by Cordilleran ice. The earliest Laurentide advance may have been the least extensive of the three Laurentide events recognized in the study area. Erratics attributed to this advance occur only east of the Halfway River – Beatton River drainage divide.

The pattern and style of deglaciation at the Late Wisconsinan Laurentide and Cordilleran ice sheet limits in northeastern British Columbia

“…29.4 ka (Klassen 1987;Catto et al 1996;Levson et al 2004;Bednarski 2001Bednarski , 2008. Paleovalleys of the Prophet and Peace rivers were infilled with proglacial permafrostrich outwash and lake sediments ("glacial Lake Mathews") then overridden by Laurentide ice (Hartman and Clague 2008;Trommelen and Levson 2008;Huntley and Hickin 2010). Advance stage glacial lake deposits reported by Huntley et al (2011) are equivalent in age and depositional environment to those associated with glacial Lake Mathews, but there is no evidence to suggest these water bodies were connected.…”

“…The glacial history of the region outlined here is constrained by 14 C ages of organic material, 230 Th/ 234 U isotopic ages of speleothems, cosmogenic ages of glacial erratics, and optical ages of dune fields in adjacent areas of British Columbia, Yukon, and Northwest Territories (e.g., Ford 1976;Mathews 1980;Rampton 1987;Rutter et al 1993;Lemmen et al 1994;Duk-Rodkin and Lemmen 2000;Smith 2000Smith , 2002Bednarski and Smith 2007;Bednarski 2008;Hartman and Clague 2008;Trommelen and Levson 2008;Demchuk 2010;Huntley et al 2011;Hickin et al 2015Hickin et al , 2016. Radiocarbon ages are converted to approximate corresponding calendar years BP (ka) using the calibration model of Reimer et al (2009).…”

“…The relatively subdued topography of northeastern British Columbia does not reflect the irregular, buried bedrock surfaces. Mountains, foothills, and high plateaus were deeply incised by preglacial rivers, and their paleovalleys were subsequently infilled with a succession of Pleistocene sediments during multiple cycles of glaciation (Hartman and Clague 2008;Hickin et al 2008;Trommelen andLevson 2008, Hickin et al 2016). For example, valley fill successions described by Trommelen and Levson (2008), 100 km south of the study area contain wood dated ca.…”

“…8A) are indicative of initial advance of ice margins over sand and clay-rich bed materials containing permafrost (cf. Dyke and Prest 1987;Johnson 1990;Kleman and Borgström 1994;Bennett et al 1998;Boulton et al 1999;Ó Cofaigh et al 2005;Bednarski 2008;Evans et al 2008;Hartman and Clague 2008;Hickin et al 2008;Trommelen and Levson 2008;Benediktsson et al 2009;Lajeunesse 2014;Hickin et al 2016).…”

“…Surficial geology mapping and fieldwork in northeastern British Columbia over the last 50 years have established that meltwater spillways and glacial lakes formed along retreating margins of the Late Wisconsinan (Late Pleistocene Marine Isotope Stage 2) Cordilleran and Laurentide ice sheets (Mathews 1980;Smith 1992Smith , 1994Lemmen et al 1994;Duk-Rodkin et al 1996;Teller et al 2002Teller et al , 2005Dyke et al 2003;Zazula et al 2004;Bednarski and Smith 2007;Bednarski 2008;Hartman and Clague 2008;Trommelen and Levson 2008;Hickin et al 2015Hickin et al , 2016. In the context of landsystem models of past ice sheets and observations of modern dynamic ice sheet behaviour, outstanding questions remain regarding (1) the limits of Laurentide and Cordilleran ice sheets in the region, (2) patterns and relative timing of ice retreat, (3) the sources and influences of meltwater on ice sheet dynamics during deglaciation, (4) evolution of meltwater drainage routes, and (5) elevation limits and extent of proglacial lake formation.…”