Controls on glacial divide migration in Southern Canadian Rocky Mountain fold and thrust belt

The present-day landscape of Southern Canadian Rocky Mountains is a product of the interaction among tectonics, lithologic resistance, and surface processes including erosion by rivers and glaciers. Rivers have adjusted to the orogeny-associated structures, regional tectonic uplift and growing terrain slope, and post-orogenic, extensive glaciation by modifying their channel profile and planform geometry. Understanding the relationship between fluvial and glacial erosion is crucial, as not only does it reflect the landscape’s sensitivity to the climate change, but also because it can indicate whether glacier-driven stream piracy (and basin reorganization) can cause significant downstream discharge alterations. The mechanisms of glacial headwall erosion, drainage divide migration, and resulting stream capture, still form a considerable research gap in landscape evolution studies. The Canadian Rockies provide an excellent opportunity for understanding the progression of subglacial channel network geometry and related basin reorganization. This study aims to evaluate glacial headwall erosion processes in glaciated headwaters through progressive divide lowering, lateral migration, and stream capture. We remotely analyze topographic features, corroborating them in the field. We completed the morphometric investigation using the MATLAB based TopoToolbox, Topographic Analysis Kit, and a customized DivideMigration function. We observe two unique signatures of glacial divide migration in the Canadian Rockies: (1) breached drainage divides that suggest lateral erosion by glaciated headwaters directed along weak lithologies and (2) the presence of low relief, high elevation divides without headwall preservation, possibly indicating periods of paleo-drainage capture during glaciation. Our preliminary results have implications for the role of glacial erosion in reshaping the landscape with respect to the structure, lithology, and climate.