HOLOCENE HISTORY OF THE COLUMBIA ICEFIELD, CANADA (Invited Presentation)

The Columbia Icefield is the largest icefield in the Canadian Rockies and feeds seven major glaciers that drain to three different oceans. Previous glacier studies have focused on Athabasca and Saskatchewan Glaciers, primarily due to their easy access. This paper reviews evidence of the Holocene history from all seven glaciers.

Maximum Holocene glacier extent was during the Little Ice Age (LIA) with dating based mainly on minimum tree-ring estimates from trees growing on the moraines or from trees scarred, tilted or killed by the glaciers. The LIA maximum advance was during the 19^th century at Athabasca (1843/4), Dome (1846), Saskatchewan (1864), Columbia (<1852) and Castleguard (<1858) Glaciers but during the 18^th century at Manitoba (<1739), Kitchener (<1713) and Stutfield (1758). Earlier LIA advances are identified from a buried in-situ tree at Stutfield (>1271) and detrital wood from lateral moraines at Manitoba (>1474) and Columbia (0.8-0.7 ka, 0.7-0.5 ka, 0.5-0.3 ka) Glaciers. There are also undated (pre-1600) moraines at Kitchener Glacier.

Less extensive pre LIA glacier events are documented by an in-situ forest bed buried by the Saskatchewan Glacier (ca 2.90–3.4 ka., “Peyto advance”) from wood in till dated ca. 2.5 ka at Stutfield Glacier and ca. 1.7-2.7ka. at Columbia Glacier plus buried wood and soil at adjacent Boundary Glacier (ca 4.8 and 4.1 ka). Detrital wood from glacier forefields dating ca 6.0 (Dome), 7.0 (Dome, Athabasca) and ca 9.0 ka (Athabasca) indicate forested areas existed upvalley of present glacier fronts at those times and may represent wood killed and reworked by subsequent glacier advances. Castleguard Cave is blocked by glacier ice at its upper end and a ca. 9.4ka ¹⁴C date from organic remains in the cave indicates that at least one entrance (beneath the present Icefield) was open prior to 9.4 ka, suggesting that the Icefield was much smaller, corresponding with evidence of higher treeline at this time. Although no single glacier provides direct evidence of more that two Holocene events, combining the fragmentary evidence from all glaciers reveals a much more complex Holocene glacier history.