High-latitude landscapes in the Arctic and Antarctic contain evidence of how the world's largest glaciers and ice sheets have responded to past changes in climate, and they document how glaciers erode and transport sediments and nutrients. This doctoral dissertation research project will examine an area of northwestern Greenland as a natural laboratory that can be used to study high-latitude landscape evolution on timescales of tens to hundreds of thousands of years. The doctoral student will analyze two distinct units of glacial sediments that have been deposited in different but adjacent areas in the Thule region in order to determine how each of the sedimentary units has evolved over space and time and use these insights as a model for understanding landscape evolution and sediment transport in glaciated high-latitude regions, including locations in northern North America and other high-latitude landscapes where similar processes are functioning. The project will provide valuable new information about the timing of past episodes of ice sheet advance and retreat. It will help address the question of whether glacial ice has behaved as an agent of erosion, and it will enhance scientific understanding of the complex processes that shape high-latitude landscapes. Cosmogenic data will be made accessible to other researchers via the NOAA paleoclimatology database, and project findings will be disseminated through both scholarly and popular media in order to broaden the range of individuals who may benefit from the new insights and information that will be generated. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.
The high-latitude landscapes that are the focus of this project are shaped by a cyclic pattern of glacial advance and retreat. During glacial periods, when ice sheets expand, the landscape can either be deeply eroded and sculpted by glacial ice (if the ice is at the melting point and liquid water is available) or preserved beneath non-erosive glacial ice (if the ice is below the melting point and frozen to the bed). During interglacial periods when ice sheets shrink, weathering modifies the landscape through movement of material by wind, water, and freeze-thaw action. Subsequent smaller ice advances may cover only part of the landscape, creating geographies where surfaces with different ages and histories are juxtaposed. The doctoral student will reconstruct the complex landscape history in the Thule region through the analysis of three rare isotopes: beryllium-10, aluminum-26, and carbon-14. These isotopes build up slowly in rock surfaces only when the rocks are exposed and not covered by glaciers. The analyses of the concentrations of these isotopes in rock surfaces will provide information about the age and exposure history of the landscape .
