Medial moraines as part of a glacier debris system : their formation and sedimentology

TL;DRAbstract

The morphological development of medial moraines on Austerdalsbreen, Norway and Berendon Glacier, British Columbia is dependent upon englacial debris supply. A literature review suggests that this is a general case. An 'ablation-dominant' model of moraine formation is proposed which relates englacial debris supply to the site and manner of englacial incorporation of debris relative to the firn line. On Austerdalsbreen a prominent medial moraine is formed by the confluence of two ice-cap outlet glaciers below the firn line (below firn line subtype of the model). Moraine debris is derived from extraglacial bedrock outcrops between the two ice streams and is englacially entrained via crevasses to which lower depth limits apply. Revelation of crevasse-bound debris generates a distinct ice-cored morphology which is destroyed as crevasse-bottoms are revealed downglacier. In this below firn line subtype, moraines formed by confluence of ice-cap outlet glaciers below the firn line are characte

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