Pattern and chronology of glacial Lake Peace shorelines and implications for isostacy and ice‐sheet configuration in northeastern British Columbia, Canada

• Published in: Boreas
• Main Authors: Hickin, Adrian S., Lian, Olav B., Levson, Victor M., Cui, Yao
• Other Authors: BC Ministry of Energy and Mines
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2015
• Subjects: Ice Sheet
• Online Access: http://dx.doi.org/10.1111/bor.12110; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fbor.12110; https://onlinelibrary.wiley.com/doi/pdf/10.1111/bor.12110

Recognition of positions of glacial lakes along the margin of continental ice sheets is critical in reconstructing ice configuration during deglaciation. Advances in remote sensing technology (e.g. LiDAR ) have enabled the generation of accurate digital‐elevation models ( DEMs ) that reveal unprecedented geomorphic detail. Combined with geographical information systems, these tools have considerably advanced the mapping and correlation of geomorphic features such as relict shorelines. Shorelines of glacial L ake P eace ( GLP ) developed between the L aurentide and C ordilleran ice sheets in northeastern B ritish C olumbia and northwestern A lberta. Shoreline mapping from high resolution DEMs produced more than 55 500 elevation data points from 3231 shorelines, enabling the identification of four major phases of GLP : Phase I (altitude 960–990 m a.s.l.); Phase II (890–915 m a.s.l.); Phase III (810–865 m a.s.l.); and Phase IV (724–733 m a.s.l.). The timing of Phase II of GLP is estimated by two optical ages of <16.0±2.5 and 14.2±0.5 ka BP . Extensive mapping of the shorelines allows for measuring of glacial isostatic adjustment as ice retreated. Shorelines currently dip to the northeast at around 0.4–0.5 m km −1 . This slope reflects the asynchronous retreat of the C ordilleran ( CIS ) and L aurentide ( LIS ) ice sheets. The relative uplift in the southwest of the study area within the R ocky M ountains and foothills suggests that the Late Wisconsinan ( MIS 2) CIS persisted in the foothill after the LIS lost mass and retreated, or that the Late Wisconsinan CIS was very thick and caused deep crustal loading, which resulted in more uplift in the southwest before reaching equilibrium during, or shortly after deglaciation.