See more from this Division: General Discipline Sessions
See more from this Session: Geomorphology
Abstract:
Well-defined geomorphic relationships expressed in the LiDAR data offer an attractive alternative interpretation. A distinct pattern of cross-cutting moraines, till-plains, and marine strandlines indicate that 1) there was only a single transgression in the region to ~100 m asl following initial retreat of the Puget Lobe (indicated by shells in the basal Bellingham drift), 2) this transgression was driven by rapid eustatic sea level rise that temporarily outpaced the local isostatic rebound, 3) the transgression was closely followed by (and possibly caused) a late-glacial readvance that culminated in Bellingham Bay, and 4) isostatic rebound then surpassed eustatic rise, coincident with final glacier retreat. Deposits previously mapped as Sumas terminal moraines instead appear to be recessional moraines from this more-extensive Bellingham Bay advance. Also, geomorphic relationships indicate that the Bellingham drift transitions from glacial marine at its base to till at its top, coincident with the regression. The close timing between transgression and advance, and regression and retreat, suggests a dynamic cause (i.e., reduced basal shear stress from marine inundation) for the Bellingham Bay advance.
See more from this Division: General Discipline Sessions
See more from this Session: Geomorphology