Neoglacial Glacier Fluctuations in the Canadian Rockies

Abstract

The Little Ice Age was the most extensive Neoglacial glacier advance in the Canadian Rockies. Evidence of earlier, less-extensive Neoglacial glacier advances is based on wood recovered from several glacier forefields. Wood flushed out of Athabasca Glacier (7550-8230 yr B.P., three dates) and Dome Glacier (6120-6380 yr B.P., two dates) indicates that forests occurred upvalley of present glacier termini during the Hypsithermal. Detrital logs from Peyto (14 dates), Saskatchewan (3 dates), Robson (3 dates), and Yoho (1 date) Glaciers, plus in situ slumps at Peyto and Robson Glaciers, have yielded 14 C dates between 2490 and 3300 yr B.P. (12 dates between 2800 and 2990). This wood is derived from sources at or upvalley from present glacier termini and represents forests overridden by glaciers between ca. 3100 and 2500 yr B.P. (Treeline was higher than present immediately prior to this advance.) This advance, which did not extend beyond the Little Ice Age maximum position, is designated the Peyto Advance and correlated with the Tiedemann Advance in western British Columbia. Earliest Little Ice Age advances at Peyto and Robson Glaciers are dated ca. 800-600 yr B.P. at positions ca. 500 m upvalley from Little Ice Age limits.

Postglacial vegetation and climate dynamics in the Seymour‐Belize Inlet Complex, central coastal British Columbia, Canada: palynological evidence from Tiny Lake

“…Both species require wet and cool conditions, so their occurrence at Tiny Lake at this time is interpreted to mark the establishment of a modern temperate and wet climate (Krajina, 1969). This event is correlative with the onset of cooler and moister conditions (Porter and Denton, 1967;Mathewes, 1973;Ryder and Thompson, 1986;Luckman et al, 1993). Peak expansion of Cupressaceae at Tiny Lake at ca.…”

Deglaciation of the Cordillera of Western Canada at the end of the Pleistocene

“…Basal sediments in a lake 0.5 km downstream of one such moraine in the southern Coast Mountains yielded a radiocarbon age of 9680 ± 40 14 C yr BP (11,200-10,800 years ago), which is a minimum for the age of the advance that constructed the moraine (Minkus, 2006). Similarly, glaciers either formed anew or advanced from cirques in the southern Rocky Mountains during the Crowfoot Advance near the end of the Pleistocene (Luckman and Osborn, 1979;Osborn and Gerloff, 1997). Reasoner et al (1994) correlated construction of the type Crowfoot moraine to deposition of sediment in adjacent Crowfoot Lake, which they dated to 13,000-11,500 years ago.…”

Subglacial methanogenesis: A potential climatic amplifier?

“…Some proglacial material is bulldozed into push moraines and thrust ridges during glacial advance, but a significant amount of sediment and vegetation is overridden by advancing ice [Winkler and Nesje, 1999;Motyka and Echelmeyer, 2003]. In support of this are numerous incidents of fossil carbon found in glacial till [Simpkins and Parkin, 1993;Punkari and Forsström, 1995;Wiles et al, 1999], and reports of Holocene forests being buried by advancing ice [Luckman et al, 1992[Luckman et al, , 1993Luckman, 1995;Motyka and Echelmeyer, 2003]. Simpkins and Parkin [1993] demonstrate that methane continues to be produced in these tills from OC that is 14 -17 ka old.…”

“…We include only soil carbon in this minimum estimate, assuming that vegetation died off prior to ice advance. Since there is sedimentary evidence that ice did override forest both during the last glacial period and the Holocene [Simpkins and Parkin, 1993;Punkari and Forsström, 1995;Luckman et al, 1992Luckman et al, , 1993Luckman, 1995], we do not consider scenario B to be entirely realistic. There is evidence, however, that some vegetation change did take place in North America and Europe as the ice sheets built up, with tundra becoming more abundant [Prentice et al, 2000].…”