| Summary: | Advisors: Ross D. Powell. Committee members: Reed P. Scherer; Nathan D. Stansell. Includes bibliographical references. Includes illustrations. Processes mediating the interaction between ice sheets with the ocean and with their beds contributes the largest source of uncertainty in projections of global sea-level rise. Yet, accessing the ice-sheet bed and ocean boundary directly are challenging and in most cases prohibitive. As a consequence, our understanding of these environments relies heavily on inference from theory, remote sensing, and the geologic record of past ice-contact deposits. Although these support important insights, critical gaps remain. Many hypotheses are essentially untested and significant uncertainty remains in their applicability and in how remote sensing and geologic data should be interpreted. This dissertations helps to fill that observational gap through a series of case studies examining modern grounding zones, thereby providing new insight into a range of topics including (1) the organization of the subglacial hydrologic system beneath an Antarctic ice stream, (2) ocean circulation to ice-shelf grounding zones, (3) depositional processes at a polar ice-stream grounding zone, (4) how grounding-zone deposits record conditions at ice-sheet margins, (5) controls on glacial erosion, and (6) the capacity for sediment deposition at grounding zones to stabilize ice sheets and glaciers against climate change. Ph.D. (Doctor of Philosophy)
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