Impact of multiple glacier surges—a geomorphological map from Brúarjökull, East Iceland

Abstract

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Simultaneously with geological field investigations at the surge-type glacier Brúarjökull in August 2003, aerial photographs covering the central part of the glacier including the Kringilsárrani area were recorded with the purpose of mapping glacial landforms. A glacial geomorphological map has been completed at a scale 1:16,000 including more than 20,000 landforms from an area of c. 8 km². Manual classification of landforms was carried out directly in stereoscopic view using a digital photogrammetric workstation taking full advantage of the texture, topography and spatial context of individual landforms. We mapped subglacial lineations such as flutes and drumlins on till plains, pitted outwash, eskers, minor meandering ridges, crevasse fill ridges, ice-free dead-ice moraine and concertina ridges, outwash fans and lake sediment plains. In addition, erosional drainage channels, ice-marginal ridges, overridden end-moraines, and extra-marginal ice wedge polygons and collapsed palsas were mapped. The mapped glacial landforms originate from at least four surges: pre-1810, 1810, 1890 and 1964. The distribution of landforms on the Brúarjökull fore-eld has close resemblance to landform assemblages of palaeo-ice streams. The present terrain surface at Brúarjökull is the cumulated result of multiple landform generations because each surge has superimposed a new association of landforms on older surfaces.