Little Ice Age history of Tzeetsaytsul Glacier, Tweedsmuir Provincial Park, British Columbia

Abstract

This paper describes licheno- metric and dendroglaciological investigations of Little Ice Age (LIA) deposits at Tzeetsaytsul Glacier, Tweedsmuir Provincial Park, British Columbia. The glacier originates from an ice- field on the northeast flank of Tzeetsaytsul Peak and terminates in a moraine-dammed lake. A stream draining the lake has incised the moraine dam and flows through nested moraines into a second lake. Two end moraines near the lower lake record separate advances, with numerous morainic ridges found between the two lakes. A locally calibrated Rhizocarpon geographicum growth curve was constructed and provides relative ages for all the moraines. Absolute dates from wood fragments collected from within the morainic debris were determined by matching their annual growth ring patterns to a local Abies lasiocarpa tree-ring chronology. The outermost terminal moraine was deposited by a 17th century advance that culminated in ca. 1700. Following subsequent recession, Tzeetsaytsul Glacier readvanced to build a second terminal moraine by the mid-1800s. Recession of this glacier occurred within 40 years and by 1935 the glacier was beginning to calve into the uppermost lake. The research shows that the most recent LIA advance of Tzeetsaytsul Glacier was not the most extensive, and that multiple events characterized the late-LIA. Application of the Rhizocarpon growth curve indicates a previously unreported 17th century advance at other glaciers in the region. These findings serve to reinforce the synchroneity of late-LIA glacier fluctuations within the coastal cordillera of NW North America suggesting that they record regional climate forcing.

Glacier fluctuations during the past millennium in Garibaldi Provincial Park, southern Coast Mountains, British Columbia

“…The Cascades curve (Porter 1981;O'Neal and Schoenenberger 2003) seems to work for the youngest moraines, but gives inconsistent ages for moraines predating the late 19th century. A curve from the central Coast Mountains (Smith and Desloges 2000;Larocque and Smith 2004) consistently overestimates the ages of moraines in Garibaldi Park. Growth rates may be higher on Vancouver Island, the Cascade Range, and Garibaldi Park than in the mountains of central British Columbia because of more favourable ecological conditions (Larocque and Smith 2004).…”

“…b Porter (1981); O'Neal and Schoenenberger (2003). c Smith and Desloges (2000); Larocque and Smith (2004). sites c and i (r = 0.494), suggesting that the trees from which the samples were derived were overridden by the glacier at either the same site or at different sites at about the same time.…”

“…200 km to the west (Lewis 2001;Lewis and Smith 2004a); (2) the Bella Coola and Mount Waddington area, ca. 200-350 km to the northwest (Smith and Desloges 2000;Larocque and Smith 2004); and (3) the Cascade Range in Washington, ca. 100-350 km to the south (Porter 1981;O'Neal and Schoenenberger 2003).…”

“…Most research on Little Ice Age glacier fluctuations in western Canada has been conducted in the Rocky Mountains (Luckman 2000, and references therein). Less is known about glaciers in the Coast Mountains (Mathews 1951;Ryder and Thomson 1986;Desloges and Ryder 1990), although there are now well-dated records from Vancouver Island and the adjacent British Columbia mainland (Smith and Desloges 2000;Larocque and Smith 2003;Lewis and Smith 2004a).…”

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

“…Radiocarbon dates on wood detritus and buried boles show that Bug glacier, Two glacier, and Todd Glacier were all advancing into valley bottom forests 500 to 400 years ago. This advance likely corresponds to moraines constructed by glaciers farther south in the central Coast Mountains in the early-to mid-1700s A.D. (Desloges and Ryder 1990;Smith and Desloges 2000;Larocque and Smith 2003). This observation is supported by trees killed in 1746 and 1764 A.D. at Surprise glacier when debris spilled down the distal moraine slope.…”