Relict non-glacial surfaces in formerly glaciated landscapes |
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Institution: | 1. School of Earth and Ocean Sciences, University of Victoria, Victoria, BC V8P 5C2, Canada;2. Geological Survey of Canada—Pacific, Natural Resources Canada, Sidney, BC V8L 4B2, Canada;3. Geological Survey of Canada—Atlantic, Natural Resources Canada, Dartmouth, NS B2Y 4A2, Canada;4. Department of Geography, Memorial University, St. John''s, NL A1B 3X9, Canada;5. Paleotec Services, Ottawa, ON K1R 5K2, Canada;6. Geological Survey of Canada—Northern, Natural Resources Canada, Ottawa, ON K1A 0E8, Canada;7. Canadian Geodetic Survey, Natural Resources Canada, Sidney, BC V8L 4B2, Canada;1. Centre for Earth Evolution and Dynamics, University of Oslo, Blindern, 0316 Oslo, Norway;2. Det norske oljeselskap, Bryggetorget 1, Aker Brygge, 0250 Oslo, Norway;1. Department of Physical Geography and Quaternary Geology, Stockholm University, S-10691 Stockholm, Sweden;2. School of Geography and GeoSciences, University of St Andrews, Irvine Building, North Street, St Andrews, KY16 9AL Fife, Scotland, UK |
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Abstract: | Relict non-glacial surfaces occur within many formerly glaciated landscapes and contain important information on past surface processes and long-term landscape evolution. Relict non-glacial surfaces are distinguishable from glacial surfaces by large-scale morphologies, including rounded summits, fluvial valleys, and cryoplanation terraces and pediments, and the presence of tors, blockfields, and/or saprolites. Preservation during glaciation occurs either through coverage by non-erosive, cold-based, ice or as nunataks. Although surface morphologies and denudation rates indicate a continuous non-glacial surface history since preglacial times, relict non-glacial surfaces are dynamic features that have evolved during the Quaternary. Depending on spatial variables such as lithology, slope, regolith depth and the abundance of fine matrix and water some surfaces are denuding very slowly, while others display more rapid denudation. High spatial variability in denudation rates results in changing surface morphologies over time. Denudation rates also display high temporal variability, with much surface evolution having perhaps occurred soon after the initial onset of glaciation or during paraglacial phases. While some parts of non-glacial landscapes are currently active, others may be largely inactive relicts of past higher energy regimes. Although non-glacial surfaces are dynamic much remains to be determined regarding surface denudation rates and the magnitude of morphological changes over time. |
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