LATE HOLOCENE GLACIERS AND AVALANCHE ACTIVITY IN THE ALFOTBREEN AREA,WESTERN NORWAY - EVIDENCE FROM A LACUSTRINE SEDIMENTARY RECORD

Deposits from the proglacial lake Grondalsvatn in the vicinity of Angs trom lfotbreen, the westernmost glacier in southern Norway, show evide nce of avalanches that descended into the lake between at least 2910 /- 60 and 2590 +/- 60 C-14 yr BP (1170-770 cal. BC). A possible short glacial period from 2590 +/- 60 to 2140 +/- 60 C-14 yr BP (330-60 cal. BC) is thought to be represented by a thin, grey silt interlayer. Aft er this date, the inflow of glacial meltwater to the lake ceased, indi cating that few or no glaciers existed on the Angstrom lfotbreen plate au at that time. A drop in organic-matter content and an associated in crease in clastic-material supply at the cure depth of 100 cm may indi cate some renewed glacial activity in the lake's catchment from about 1650 +/- 60 C-14 yr BP (cai. AD 370-450). The textural and carbon-cont ent change at about 60 cm depth indicates an increased Neoglacial acti vity in the catchment from 910 +/- 70 C-14 yr BP (cal. AD 1030-1220). The winter snow-mass balance is the most important factor controlling the net mass balance of Angstrom lfotbreen.