Little Ice Age Snow-Cover Extent and Paleoglaciation Thresholds: North-Central Baffin Island, N.W.T., Canada

Abstract

On air photographs, light-colored areas representing reduced lichen cover indicate the maximum extent of permanent snow cover in the recent past. Lichen-free areas were mapped on 1:50,000, 1:250,000 and 1:1,000,000 map sheets of north-central Baffin Island using air photographs and LANDSAT-1 satellite imagery. Present ice and lakes cover 37% of the study area (97,000 km2). During the Little Ice Age (350-100 yr BP), ice and lakes covered about 50% of the study area, an increase of 35%. The amount of lichen-free area is greatest in the elevational range of 450-600 m a.s.l. A limited amount of lichenometrical measurements indicate that the lichen-free areas probably represent a period of more extensive snow cover approximately synchronous with the Little Ice Age. Paleoglaciation thresholds and paleoequilibrium-line altitudes increased in elevation toward the northeast with lowest elevations southwest of the Barnes Ice Cap. Paleoglaciation thresholds ranged from 500-850 m a.s.l. (above sea level); paleoequilibrium-line altitudes ranged from 300-900 m a.s.l. Present glaciation thresholds and equilibrium-line altitudes ranged from approximately 100-400 m higher than the paleovalues. The difference between present and paleovalues is greatest over the mountainous east coast and decreases to the west.