Topographic control of equilibrium-line altitude depression on reconstructed 'Little Ice Age' glaciers, Grovabreen, western Norway

Abstract

'Little Ice Age' marginal moraines in the Grovabreen area, inner Sunnfjord, are mapped and described. The modem and 'Little Ice Age' (mid-eighteenth century) equilibrium-line altitude (ELA) of the plateau glacier Grovabreen is calculated by the use of an accumulation-area ratio (AAR) of 0.6, giving a 'Little Ice Age' ELA depression of 125 m. AAR-ELA depression of the 'Little Ice Age' glaciers is also calculated for northern and southern outlet glaciers. Different estimates are considered to be the result of topographic differences. Other methods, such as the mean elevation of glaciers (MEG) and the toe-to-headwall altitude ratio (THAR), gave ELA depressions of 260 m and 315 m, respectively. These differences, due to topographic conditions, indicate that only glaciers with a uniform slope should be used to calculate the regional ELA of former glaciers.