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A Pebble Count Comparison And Rock Magnetism Provenance Study Of Sumas Outwash, Jeff Laub

WWU Graduate School Collection

The Sumas Stade, the last of the Fraser Glaciation advances, occurred between 12,000 and 10,000 ¹⁴C years B.P. This study combines previous mapping (Easterbrook, 1976; Haugerud, written communication, 1999) with three new tests to establish a chronology for events of the Sumas Stade. Comparison of compositions of pebbles from Sumas outwash using multivariate statistics such as hierarchical clustering and k-means clustering revealed three major groups of late Sumas outwash and one earlier deposit. Magnetic susceptibility and Curie temperature analysis determined a general British Columbia provenance for the Sumas outwash. Flow direction measurements substantiated this determination. Taken together, these tests …