Ice-penetrating radar produces detailed images of the internal layers of ice in a glacier. Because the layers form from each year's snowfall, the curving and folding of the internal layers are a record of the climate conditions and perturbations that the glacier experienced as it flowed throughout the millennia. The Hiawatha Glacier lies on top of a meteor crater, 30km in diameter and estimated to be ~58 million years old. Airborne radar surveys of the Hiawatha structure show unusually complex internal layering which may be the result of basal freezing and melting, accumulation, or the bedrock topography of the meteor crater. The complexity of basal processes and limited climate data are significant challenges in quantitative models of ice flow. Previous investigations indicated that the slopes of the internal layers alone may be useful indicators of the aforementioned climate boundary conditions that result in internal layer deformation. Analyzing the slopes of the layers in one central Hiawatha radargram, we match distinct signals in the internal layer shape to particular formation mechanisms. We identify possible signals of basal melt, freezing, frictional changes, and accumulation across two cross-sections from Hiawatha Glacier. We conclude that the layer slope technique is a useful tool to provide qualitative guides to basal friction and melt to aid in ice flow modeling.

Georgia Carroll is a senior in Physics. Her research is supervised by Prof. Erin Pettit.