MULTICENTURY GLACIER FLUCTUATIONS IN THE SWISS ALPS DURING THE HOLOCENE

Abstract

Subfossil remains of wood and peat from six Swiss glaciers found in proglacial fluvial sediments indicate that glaciers were smaller than the 1985 reference level and climatic conditions allowed vegetation growth in now glaciated basins. An extended data set of Swiss glacier recessions consisting of 143 radiocarbon dates is presented to improve the chronology of glacier fluctuations. A comparison with other archives and dated glacier advances suggests 12 major recession periods occurring at 9850- 9600, 9300-8650, 8550-8050, 7700-7550, 7450-6550, 6150-5950, 5700-5500, 5200-4400, 4300-3400, 2800-2700, 2150-1850, 1400-1200 cal. yr BP. It is proposed that major glacier fluctuations occurred on a multicentennial scale with a changing pattern during the course of the Holocene. After the Younger Dryas, glaciers receded to a smaller extent and prolonged recessions occurred repeatedly, culminating around 7 cal. kyr BP. After a transition around 6 cal. kyr BP weak fluctuations around the present level dominated. After 3.6 cal. kyr BP less frequent recessions interrupted the trend to advanced glaciers peaking with the prominent ‘Little Ice Age’. This trend is in line with a continuous decrease of summer insolation during the Holocene.