INTERPRETING GLACIAL CHRONOLOGIES IN THE MONGOLIAN ALTAI USING DRONE-DERIVED MAPS

We use ¹⁰Be surface-exposure dating of glacially deposited boulders to reconstruct the glacial history of the Potanin Glacier valley in the Mongolian Altai during the last termination (~11-19 ka). In order to create a reliable chronology, it is vital to have a firm understanding of the geomorphology of the study area for two reasons. First, glacial geomorphic maps provide information about the geometry and dynamics of past glaciers. Second, surface-exposure dating operates under the assumption that the glacially deposited boulders have not been disturbed after the original deposition. Information about landscape changes informs our assessment of boulder stability. We use glacial geomorphic maps derived from structure-from-motion analysis of drone imagery to produce high-resolution digital elevation models (DEMs) and ortho-imagery. With these data sets and field observations, we create detailed geomorphic maps and determine geomorphic mechanisms that could yield surface-exposure age scatter. High-resolution drone imagery has proven enormously useful in making the geomorphology interpretations that underpin our glacial chronology.