Title: Tracking "Ghost Glaciers" Using Cosmogenic Nuclides
Abstract: The traditional view of glaciers is that they are highly erosive, efficiently move large amounts of material, and significantly sculpt and shape the underlying landscape. But in certain situations, the base of the glacier remains below the pressure melting point and frozen to the bed, inhibiting the glacial ice from abrading or plucking the underlying material; such "ghost glaciers" leave no physical evidence of their presence on the landscape once they have disappeared in a warmer climate. Finding evidence for now-vanished cold-based, non-erosive glacial ice has long represented a challenge, particularly in high-latitude and/or high-altitude environments. Because of the dearth of physical evidence, I use cosmogenic nuclides to study the burial of rock surfaces by "ghost glaciers" in the past. The use of multiple cosmogenic nuclides with different half-lives allows me to quantify when and for how long surfaces have been buried beneath ice, even though the ice did not physically alter those surfaces. Gaining a better understanding of now-vanished glacial ice, including elusive non-erosive ice, provides insight about past climates, sediment transport, and landscape formation over long timescales.
Bio: Dr. Lee Corbett is the manager of the Community Cosmogenic Facility at University of Vermont; she collaborates with and hosts visitors from around the world to learn methods and prepare their own samples for studying a diverse array of Earth surface processes using cosmogenic nuclides. Lee's own research interests are focused on understanding how glacial landscapes evolve over long timescales, how glaciers move sediment, and how glacial sediment can be used as an archive of climate information. Because of her role managing the laboratory, she works on a wide range of projects including quantifying erosion rates, studying river and hillslope systems, dating recent tectonic activity, and investigating glacial history and retreat rates. Lab Website