Lacustrine sediment records of debris flow activity, northwestern British Columbia and southwestern Yukon Territory

• Main Author: Van Brabant, Reid
• Format: Others
• Language: en
• Published: University of Ottawa (Canada) 2013
• Subjects: Geography.; Geology.
• Online Access: http://hdl.handle.net/10393/26791; http://dx.doi.org/10.20381/ruor-18373

Lacustrine sediment records were used to examine debris flow magnitude and frequency at two sites in northwestern Canada. A rod-driven piston corer was used to collect four lacustrine sediment cores from Mount Aramis Lake, Yukon Territory (YT) and five from Three Guardsmen Lake, British Columbia (BC). Nine layers deposited in the Lacustrine sediment of Mount Aramis Lake over an estimated 3400 to 3800 yrs and ten layers deposited in Three Guardsmen Lake over an estimated 3000 to 3500 yrs are inferred to be due to debris flows. However, these layers represent the minimum number of events because lacustrine sediments only contain a record of debris flows with sufficient energy to reach the lake. Variations in the sedimentary structure of the debris flow layers between the sites could not be attributed to differences in debris flow magnitude and frequency resulting from local variations in slope gradients, debris supply, or precipitation. The lacustrine, terrestrial, and climatic evidence indicates that lower precipitation at Mount Aramis may result in higher magnitude, lower frequency debris flows. Conversely, higher precipitation at Three Guardsmen Mountain may cause lower magnitude, higher frequency debris flows. However, these are preliminary conclusions and further research regarding the relationship between precipitation regime, debris supply, and debris flow magnitude and frequency is required.