Terminal moraine formation processes and geomorphology of glacier forelands at the selected outlet glaciers of jostedalsbreen, south norway

Abstract

Several outlet glaciers of Jostedalsbreen flow from the central plateau ice-cap into surrounding valleys. A well-established Holocene glacier chronology reveals that the ‘Little Ice Age’ with its culmination ~1750 CE was the most prominent neoglacial event in the region. Glacial and glaciofluvial landforms on the glacier forelands are, therefore, accurately determinable in their age and allow detailed interpretation of causal relationships between geomorphology and glacier dynamics. Glacier forelands are typically characterised by a high number of comparatively small moraine ridges and wide areas of glaciofluvial outwash and glaciofluvially overprinted subglacial till deposits. A recent regional advance during the 1990s offered the unique opportunity to study terminal moraine processes. Ice pushing/bulldozing of unconsolidated proglacial sediments by the advancing glacier tongues was the dominant process, whereas seasonal advances caused the formation of subsequent moraines during or shortly after culmination of this recent advance. Recent observations serve as analogues for previous advances and allow the interpretation that differences in moraine morphology of older moraines are mainly caused by different properties of the proglacial sediment in combination with detailed dynamics of the glacier fronts. The high number of terminal moraines reveals the efficiency of short-lived and seasonal advances for moraine formation following the ‘Little Ice Age’-maximum.