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Bjørn Wangensteen Department of Geosciences University of Oslo September, 2004 PowerPoint Presentation
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Bjørn Wangensteen Department of Geosciences University of Oslo September, 2004

Bjørn Wangensteen Department of Geosciences University of Oslo September, 2004

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Bjørn Wangensteen Department of Geosciences University of Oslo September, 2004

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  1. Surface Displacement and Age Estimates for some Debris Covered Glaciers in Northern Iceland Bjørn WangensteenDepartment of Geosciences University of Oslo September, 2004 Águst Guðmundsson, Trond Eiken, Andi Kääb, Herman Farbrot, Ole Humlum and Bernd Etzelmüller

  2. Jarðfræðistofán Geological Services, Reykjavik, Iceland, Á. Guðmundsson Science Institute, University of Iceland, Prof. H. Björnsson Department of Geosciences, University of Oslo Prof. O. Humlum and asoc.prof B. Etzelmüller Main objectives of the project Assess permafrost distribution in Iceland with comparable studies in northern Norway Estimate permafrost thermal regimes and thickness in areas of high geothermal activity (Iceland) Assess rock glacier dynamics in Iceland Permafrost in northern Europe – Permafrost distribution and dynamics in Iceland and Norway

  3. This presentation focuses on mapping velocity and estimating age of slopes by digital photogrammetry Technique used for velocity mapping: Cross-correlation matching of orthophotos Displacement measurements and age estimates for Site 1 Displacement measurements and age estimates for Site 2

  4. The technique used for velocity mapping is cross-correlation of orthophotos Cross-correlation matching of orthos (CIAS) Multitemporal sets of air photos (stereo pairs) Stereomodel (DFW) + Match- T Orthophotos time 1 and 2 DTM

  5. Site 1; a debris covered glacier near Hólar

  6. Velocity measurements at site 1; the debris covered glacier at Hólar • Glacier front at 930 m.a.s.l • Lower limit of permafrost 850 - 950 m.a.s.l. • Debris cover preserves the glacier • Permafrost creep rather than glacier flow dominates in fast moving areas

  7. Age estimates for site 1;the debris covered glacier at Hólar • Trajectories based on the displacement field suggest an age of at least 4,500 to 5,000 years • This is based on an assumption of constant velocity

  8. Site 2; an ice cored moraine complex at Hólar

  9. Velocity measurements at site 2; the ice cored moraine complex • Active front at 920-30 m.a.s.l. • Lower limit of permafrost 850 – 950 m.a.s.l. • Collapsed front below. • Greatest displacement in the uppermost parts/features • Different velocities for different generations

  10. Age estimates for site 2; the ice cored moraine complex • Age of at least 1,000 – 1,500 years for the youngest generation • Oldest generation, suggested to at the age of the debris covered glacier of site 1 (4,500 – 5,000 y) • Too few measured points on the other features for a valid age estimate

  11. In summary, digital photogrammetry reveals new and promising geomorphic results Velocity fields suggest permafrost conditions Age estimates implies origin 4,500 y BP; long before the little ice age. Stable features down to 930 m.a.s.l. Questions?