Cordilleran Section - 115th Annual Meeting - 2019

Paper No. 10-4
Presentation Time: 9:00 AM-6:00 PM


GILLILAND, Amy, Geological Sciences, Central Washington University, 1262 N Walnut St, Ellensburg, WA 98926 and HUERTA, Audrey, Geological Sciences, Central Washington University, 400 East University Way, Ellensburg, WA 98926

Quantitative assessment of glacial, fluvial, and tectonic modification across the Transantarctic Mountains (TAM) is a useful tool to understand the evolution of this enigmatic landscape. This study uses geomorphometric analysis to determine the extent of different modifications across the entire length of the TAM. Future studies will relate the geomorphometric data to poorly constrained tectonic hypothesis of the TAM evolution. The TAM separate East and West Antarctica, extend over 3500 km (>30˚ of latitude), and contain hundreds of ice-covered valley networks that display a broad range of morphologies. The landscape retains the signature of fluvial, glacial, and tectonic influences. Cretaceous-Paleogene normal faulting disrupted the landscape and left extensive escarpments along the putative range front faults. Glacial erosion, the most recent modification, has scoured the TAM landscape since the Oligocene.

Previous studies from the northernmost regions of the TAM show dendritic fluvial patterns that adhere to Horton’s law of stream numbers. In this study, we us Strahler stream order and Horton’s law of stream numbers to quantitatively compare drainage networks along various regions in the TAM to fluvial-style drainage systems. In glacially modified regions (i.e. Byrd Glacier) Strahler stream order metrics differ from metrics of fluvial systems. For example, Byrd glacier (a glacially dominated drainage) has a (bifurcation ratio) of 12 when comparing the highest numbered segments to the second highest numbered segments while Lillie glacier (a fluvial dominated drainage) yields value of 4. After review of the TAM drainages in this study, it is consistent that the degree of glacial modification correlates with increasing value. To further quantify the impact of fluvial, glacial, and tectonic processes along the TAM we will use digital elevation models of the landscape to evaluate the slope, aspect, and curvature of the TAM drainages.