Deglaciation of Boknafjorden, South-Western Norway
JOURNAL OF QUATERNARY SCIENCE (2017) 32(1) 80–90 ISSN 0267-8179. DOI: 10.1002/jqs.2925 Deglaciation of Boknafjorden, south-western Norway DALE J. GUMP,1 JASON P. BRINER,1* JAN MANGERUD2 and JOHN INGE SVENDSEN2 1Department of Geology, University at Buffalo, 126 Cooke Hall, Buffalo, NY 14260, USA 2Department of Earth Science, University of Bergen, PO 7803, N-5020, Norway, and Bjerknes Centre for Climate Research, Bergen, Norway Received 29 June 2016; Revised 28 October 2016; Accepted 7 November 2016 ABSTRACT: We present 30 10Be ages from glacial erratic boulders to constrain the deglaciation of the Scandinavian Ice Sheet in the Boknafjorden region, south-western Norway. The southern part of the island Karmøy, located at the mouth of this fjord system, became free of glacier ice before 16 ka, probably because of the sudden break up of the Norwegian Channel Ice Stream at 20–18 ka. The ice sheet margin then stabilized at the fjord mouth until a second retreat phase commenced at or slightly before 16 ka. A calving bay developed in Boknafjorden after 16 ka, and in the course of the next millennium the ice front retreated to the inner fjord branches. In contrast, a major outlet glacier that filled the Hardangerfjorden farther to the north did not start to retreat from the fjord mouth until after 15 ka, probably in response to the Bølling warming. Thus, not only did Boknafjorden experience major retreat before Bølling warmth, but there was a variable response of south-western fjord glaciers in Norway consistent with prior observations of non-climatic forcing of marine-terminating outlet glaciers.
[Show full text]