The Alps with little ice: evidence for eight Holocene phases of reduced glacier extent in the Central Swiss Alps

Glacially deformed pieces of wood, organic lake sediments and clasts of rew orked peat have been collected in front of Alpine glaciers since AD 1990. T he palaeoglaciological interpretation of these organic materials is related to earlier phases of glacier recession surpassing that of today's shrunken glaciers and to tree growth and peat accumulation in the valleys now occup ied by the glaciers. Glacial transport of the material is indicated by wood anatomy, incorporated silt, sand and gravel particles, missing bark and de formed tree-rings. A total of 65 samples have been radiocarbon dated so far , and clusters of dates provide evidence of eight phases of glacier recessi on: 9910-9550, 9010-7980, 7250-6500, 6170-5950, 5290-3870, 3640-3360, 2740- 2620 and 1530-1170 calibrated years BP. Allowing for the timelag between cl imatic fluctuations, glacier response and vegetation colonization, these re cession phases may lag behind climatic changes by 100-200 years.