Observations on some Holocene glacier fluctuations in West Greenland.

Abstract

Historical and contemporary data record a major fluctuation of the position of the Inland Ice and local glaciation ice margins in the area. Regardless of the glacier type these frontal fluctuations are mostly in phase, with glacial readvances occurring around 1650(?), 1750(?), 1850(?), 1890 and 1920 A.D. Correlation with meteorological data suggests the operation of a delay of a few to twenty years before glacier response to climatic fluctuation. Whilst the individual readvances generally are recognisable throughout the area their magnitude shows a regional variation. Thus, near the coast and in South Greenland the readvances before 1850 produced the historical maximum extent of glaciers, whilst in the northernmost part of the area, Nûgssuaq peninsula and Umanak district, the advance of 1920 in part was responsible for the maximum extent. The historical frontal fluctuation corresponded with a fluctuation of the glaciation limits of 100-200 m. As a whole the deposits of the historical glacier advance form a zone marking a single stage in the extent of the glaciers. Zones of Inland Ice margin deposits of a similar magnitude of prehistoric age, have been widely recognized in the area. Three zones have been distinguished; an inner zone, an outer zone and a nunatak zone. The inner zone possibly includes several stages, but the main features date from subboreal or early subatlantic times. The outer zone comprises two stages formed at 7,500-8,500 and 9,000-9,500 B.P., whilst the nunatak zone (comprising several stages) was formed before or around 10,000 B.P. Prehistoric ice margin stages of local glaciers have been less extensively investigated. In general, they indicate only late and slight development of local glaciers due, it is believed, to the glaciation limit at the time of the retreat of the continental glaciation being already too high for their widespread development. An exception from this general trend is in the Julianehåb district where the more rapid disappearance of the continental glaciers may have favoured the better development of local glaciers.