Holocene glacier variations in central Jotunheimen, southern Norway based on distal glaciolacustrine sediment cores

Sediment cores from two glacier-fed lakes are used to reconstruct a continuous record of glacier variations since about 10,000 cal. BP in the Smorstabbtinden massif of central Jotunheinnen, southern Norway. Particular attention is paid to the century- to millennial-scale, pre-little Ice Age glacial signal based on an estimated temporal resolution of less than or equal to 55 and less than or equal to 25 yr cm(-1) for Bovertunsvatnet and Dalsvatnet, respectively. Visible lithostratigraphic variations, organic content/loss-on-ignition, calcium carbonate content, magnetic susceptibility and grain-size fractions (especially the fine silt) are used as proxy indicators of glacier presence and extent in the lake catchments. Following deglaciation, the early Holocene was characterized by generally small glaciers until a major advance (the Finse Event) peaking at approximately 8200 cal. BP. From 7900 to at least 5300 cal. BP glaciers appear to have been absent from central Jotunheimen. There is evidence of glacier expansion between about 2400 and 1600 cal. BP (the Bovertun I Event) and between about 1400 and 800 cal. BP (the Bovertun II Event) before reduced glacier extent during the Mediaeval Warm Period. Finally, the most extensive Neoglacial maximum occurred during the Little Ice Age after 500 cal. BP. In addition to providing a record of the broad pattern of climatically forced Holocene glacier variations, periodicities at 110-140, 200-285 and about 500 yr have been identified. Uncertainties remain concerning the precise timing of events, glacierization and deglacierization detection thresholds, a possible mid-to late-Holocene (5300-2500 cal. BP) Neoglacial build-up of small glaciers, and shorter-term; decadal- to century-scale variations in glacier size, for which more proximal sites are required. (C) 2000 Elsevier Science Ltd. All rights reserved.