Geomorphology and Late Wisconsinan sedimentation in the Stikine River Valley, northern British Columbia

The Stikine River Valley (SRV) contains a thick and well-exposed sequence o f Late Wisconsinan glaciolacustrine and glacial sediments. The glaciolacust rine sequences record the development of Glacial Lake Stikine (GLS), an adv ance-phase glacial lake produced when the advance of Coast Mountain glacier s impeded the westward drainage of the Stikine River. These deposits fine u pwards and fill the deeply incised pre-glacial drainage system. The thickne ss of GLS sediment indicates that a significant time-lag occurred between t he advance of alpine ice in the Coast Mountains and regional ice cover at t he study region. A deformation till and a melt-out till overlie the glacial lake sediments. The lack of any ice-directional features in the till, and the lack of lodgement till in regions covered by glaciolacustrine sediment may be an indication that thin ice with low basal shear stresses existed wi thin the SRV. Deglaciation in the SRV resulted in the formation of a comple x suite of depositional and erosional landforms. Ice persisted as a stagnat ing? down-wasting valley glacier and both subglacial and ice marginal drain age networks were most likely present. A sedimentary record of the developm ent of a retreat-phase glacial lake is not evident. Catastrophic drainage o f a Late-glacial to Holocene basalt- or ice-dammed lake was responsible for extensive erosion that created a scabland near the village of Tahltan. (C) 2000 Elsevier Science Ltd and INQUA. All rights reserved.