Max Dahlquist Sewanee - University of the South Friday, November 12, 2021 - 4:10pm Geology Colloquium - GG Building 200A or via Zoom Colloquium This is a hybrid event, if you are unable to join us in person please join via zoom. Meeting ID: 997 2477 2096 Note: A password is required to join this meeting. Please call the Geology office (706-542-2652) and speak with a representative to obtain the code. Alternatively, a code request can be made to UGA Geology. About the Speaker: Bio: Max Dahlquist is an Assistant Professor of Geology at The University of the South in Sewanee, Tennessee. He was an undergraduate at the University of Southern Indiana, earned his PhD at the University of Southern California, and did postdoctoral work at UNC-Charlotte. His research is broadly focused on how things fall apart, from individual boulders slowly fracturing apart on an alluvial fan to landslides dissecting a mountain range. He is especially interested in interplay between extreme events (i.e. earthquakes, outburst floods) and mundane (daily thermal stress, hillslope creep). He teaches physical and structural geology, sedimentology, geomorphology, and natural hazards. Outside the classroom and lab, Max and his wife Meryn are engaged in the lifelong project of raising their 3-year-old son Rookh and 1-year-old daughter Selah. Abstract: In steep landscapes, river incision sets the pace of landscape evolution. Transport of coarse sediment controls incision by evacuating material delivered to river channels by landslides. However, large landslide-derived boulders that impede bedrock erosion are immobile even in major runoff-driven floods. Glacial lake outburst floods (GLOFs) mobilize these boulders and drive incision, yet their role in regional-scale erosion is poorly understood, largely because of their rarity. Here, we find a topographic signature consistent with widespread GLOF erosion in the Nepal Himalaya. In rivers with glaciated headwaters that generate GLOFs, valleys stay narrow and relatively free of sediment, with bedrock often exposed to erosion. In turn, tributaries to these valleys are steep, allowing less efficient erosional regimes to keep pace with GLOF-driven incision. Where GLOFs are less frequent, valleys are more alluviated and incision stalls. These results suggest the extent of headwater glaciation may play an important role in erosion of Himalayan river valleys and deserves more attention in future work. Host: Rob Hawman
