|Citation||Mood, BJ. 2015. Latest pleistocene and holocene behaviour of Franklin Glacier, Mt. Waddington area, British Columbia Coast Mountains, Canada. MSc Thesis, Uvic.|
|Abstract/Description or Keywords||Holocene climate variability in the British Columbia Coast Mountains has
resulted in repeated intervals of glacier expansion and retreat. Since reaching their late
Holocene maximum positions in the late 20th
century, glaciers in the region have
experienced significant volumetric loss. The subsequent downwasting and frontal retreat
has revealed forests buried by glacier advances throughout the Holocene, enabling
description of significant intervals of ice expansion using dendroglaciology. This thesis
characterizes dendroglaciological evidence as it relates to climate at two scales: (1) at
Franklin Glacier in the Mt. Waddington area, and; (2) throughout the Coast Mountains.
Dendroglaciological evidence from glacier forefields and lateral moraines in the
Coast Mountains provides evidence for at least 11 intervals of glacier activity during the
Holocene. The earliest recorded glacier activity is documented in the Pacific Ranges from
8.5 to 8.2 ka, after which glaciers in this region retreated during the early Holocene warm
and dry interval. Following this period, glacier activity occurred from 7.3-5.3 ka in
response to attendant cool and moist conditions in the Pacific Ranges. After 5.3 ka,
glaciers in the Pacific Ranges exhibit a near-continuous record of activity from 4.8-2.5 ka
and in the Boundary Ranges at 4.1-4.0, 3.7-3.4, 3.1, 2.8-2.3 during intervals characterized
wet conditions resulting from an intense, eastwardly positioned Aleutian Low pressure
centre. Glaciers were again expanding downvalley in the Pacific and Boundary ranges
from 1.4-1.2 and 1.7-1.1 ka, respectively before contemporaneous activity from 0.8-0.4
ka during the Little Ice Age. Common intervals of glacier activity throughout the Coast
Mountains occurred at 4.1-4.0, 3.7-3.4, 3.1, 2.8-2.5, 1.4-1.2, and 0.8-0.4 ka.
Franklin Glacier is an 18-km long valley glacier that originates below the west
face of Mt. Waddington. Radiocarbon-dated wood samples from the proximal faces of
lateral moraines flanking the glacier show that it expanded at least nine times since 13 ka.
A probable Younger Dryas advance of Franklin Glacier at 12.8 ka followed the late
glacial retreat and downwasting of the Cordilleran Ice Sheet from ca. 16.0 to 12.9 ka.
During the succeeding early Holocene warm period, Franklin Glacier appears to have
retreated significantly, leaving no record of glacial expansion until the mid-Holocene
when it repeatedly advanced at 6.3, 5.4, and 4.6 ka in response to cool summer
temperatures and generally moist conditions. Downwasting of the glacier surface after
4.6 ka was followed by intervals of expansion at 4.1, 3.1, and 2.4 ka contemporaneous
with a period of increased precipitation. Following ice expansion at 2.4 ka into trees over 224 years in age, there is no record of the glacier activity until 1.5 ka when Franklin
Glacier thickened and advanced into young subalpine fir trees, reflecting attendant cool
and wet environmental conditions. During the Little Ice Age, advances at 0.8 and 0.6 ka
preceded a mid-19th to early-20th century advance that saw Franklin Glacier attain its
maximum Holocene extent in response to an extended interval of cold temperatures.
The dendroglaciological record at Franklin Glacier is among the most
comprehensive recovered from the British Columbia Coast Mountains and showcases the
complexity of latest Pleistocene and Holocene glacier behaviour in the region.
|Regional Watershed||Central Coast|
|Sub-watershed if known|
|Contact Name||Dan Smith|
|Contact Email||[email protected]|