Glacilacustrine sedimentation processes at Llewellyn Inlet, Atlin Lake, British Columbia: Implications for Little Ice Age climate change

The Llewellyn Glacier discharges from the Juneau Icefield into Llewellyn Inlet along the southwest margin of Atlin Lake in northwestern British Columbia. Patterns of sediment accumulation and deposition processes are reconstructed using Ekman, gravity and percussion cores (0.35--1.34 m) and CHIRP sub-bottom acoustics in order to establish a link between Little Ice Age (LIA) climate change and the style and quantity of sediment delivered to Llewellyn Inlet. 137Cs dating from cores demonstrate that the surface sediments are varved and allow for reconstruction of a sediment accumulation records for the last 275 years. There is a dramatic reduction in sediment delivery since 1950 related to the opening of a pro-glacial lake at the terminus of the Llewellyn Glacier. The sediment chronology matches other regional LIA glacier chronologies showing two phases of probably glacier advance, but provides a new and higher resolution record of climate-induced changes.