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

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

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 DTM Stereomodel (DFW) + Match- T Orthophotos time 1 and 2 Cross-correlation matching of orthos (CIAS) Multitemporal sets of air photos (stereo pairs)

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 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 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 Questions ? 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.