NEW TOPOGRAPHIC INSIGHTS FROM ADVANCED SWATH ANALYSIS APPROACHES USING THE TETON RANGE AS A GUINEA PIG

Swath analysis has been useful in interrogating topography for tectonic and climatic signals of uplift and erosion in tectonic-geomorphic-focused studies in a variety of settings (active ranges, plateaus, and fluvial valleys) and scales (single range to regional). The utility of swath analysis in previous studies has been limited by the need for rectangular blocks of data (elevation grids, precipitation grids, etc.) and the inability to swath irregular areas of interest despite most mountain ranges having complex boundaries defined by structure, topography, and base-level. Moreover, the orientation of cross-swaths is typically semi-perpendicular to the longitudinal axis of the range, often subjective, and difficult to reproduce. We attempted to address these issues with a Python library that can objectively orient swath profile analysis and offer options to objectively identify topographic boundaries using elevation, slope angle, topographic position index, or a custom shapefile developed from other raster analyses (i.e., roughness, aspect, relief, etc.). This flexibility provides the potential to incorporate any raster classification technique into swath analysis. Moreover, the Python library has the ability to generate differential swaths separated by a threshold such as a TPI value.

Specifically, previous studies show that the Teton Range in Wyoming displays asymmetric topography where the highest relief (>2 km) and highest peaks (Grand Teton and Mount Moran) are on the eastern side of the range near the Teton Fault. Maximum elevation is typically limited to within 1 km of cirque elevations, and the range divide has migrated westward. These observations led to an interpretation of the glaciation limiting topographic height with divide migration being driven by both uplift along the Teton Fault and climatic forces (precipitation, insolation, and redistribution of snow from wind) increasing the rate of glacier headwall sapping on the Eastern side of the range. Although these findings are sound, we generated differential swaths using topographic position index to reexamine the topography of the Teton Range and elucidate nuances that were previously unnoticed, such as patterns of interglacial erosion, vertical glacial incision, and relief trends along range strike.