Holocene development and geomorphic processes at Omnsbreen, southern Norway: Evidence for glacier–permafrost interactions

• Published in: The Holocene
• Main Authors: Lilleøren, Karianne S, Humlum, Ole, Nesje, Atle, Etzelmüller, Bernd
• Format: Article in Journal/Newspaper
• Language: English
• Published: SAGE Publications 2013
• Subjects: Paleontology; Earth-Surface Processes; Ecology; Archeology; Global and Planetary Change; Norway; glacier; Ice; permafrost
• Online Access: http://dx.doi.org/10.1177/0959683612471984; http://journals.sagepub.com/doi/pdf/10.1177/0959683612471984; http://journals.sagepub.com/doi/full-xml/10.1177/0959683612471984

Omnsbreen is a small (<0.5 km 2 ) and degrading glacier situated at the regional lower limit of present-day permafrost distribution and glaciation. At present, the existence of Omnsbreen is mainly dependent on wind-borne snow redistributed by the prevailing westerly winter-wind, and lies in an area of marginal permafrost occurrence. During the ‘Little Ice Age’ (LIA) both the glacier and the distribution of permafrost in the area reached their maximum late-Holocene areal extents. The first occurrence of Omnsbreen is recorded in sediment cores retrieved from a proglacial lake and dated at ad 1425, and marks the onset of the local LIA. Reconstruction of the maximum LIA extent by means of geomorphic indicators revealed a size of 7.1 km 2 , a volume of more than 0.25 km 3 and a maximum glacier thickness of 110 m. Since the LIA Omnsbreen has been reduced by more than 90% in area. Omnsbreen retreated rapidly from its LIA maximum, which we suggest was determined by the shape of the glacier, filling up the valley, and hence being unable to accumulate wind-borne snow. Prominent glacier marginal landforms are absent along the maximum LIA extent of Omnsbreen. We propose that the lack of glacier marginal landforms in this case is indicative of a cold glacier margin, and that the landscape evolution in maritime and marginal permafrost regions is characterised as being closely connected with glacial activity.