Dendroglaciological reconstruction of late-Holocene glacier activity at White and South Flat glaciers, Boundary Range, northern British Columbia Coast Mountains, Canada

摘要

Holocene glacier activity in the northern British Columbia Coast Mountains, Canada, is described following investigations in the recently deglaciated forefields of White and South Flat glaciers spilling from the Cambria Icefield. Glacially overridden stumps and detrital wood was radiocarbon and dendrochronologically dated to describe an advance between ad 250 and 650. Expansion and thickening of White Glacier by ad 765 resulted in creation of an ice-dammed lake in South Flat valley that persisted until ad 1080. Following this the lake drained, before refilling in the early 'Little Ice Age' prior to ad 1300. Shortly thereafter White and South Flat glaciers became confluent and flowed over the valley side toward White Lake. The characteristics of the site and the preservation of 1500 yr old deposits indicate that the two glaciers remained confluent throughout the remainder of the 'Little Ice Age', only separating following terminal retreat early in the 20th century. The late-Holocene glacial history of White and South Flat glaciers appears synchronous with those of other glaciers in northern portion of Pacific Northwest.