Kan forekomsten av laterale sedimenter ved utvalgte breer defineres som sidemorener?

Abstract

Lateral deposits alongside several glaciers located in the eastern Jotunheimen and Lyngen are observed higher up than what would be expected according to the theory on the formation of lateral moraines. By using the accumulation area ratio (AAR) of 0.6 on these glaciers the equilibrium line altitude (ELA) from the Little Ice age (LIA), and at present, were calculated. The lateral deposits occur above the estimated ELA on all glaciers with varying amount. The maximum position of lateral moraines (MELM) is also a method used to estimate ELA, but the data in this study suggests that by using all of the lateral deposits as the basis for these estimations the accumulation area ratio under LIA must have been varying from 10 to 44 % on these glaciers. This will most likely underestimate the ELA on glaciers under this period. It is suggested that they are deposited because of increased rockfall and debrisfall during the LIA, which have made ice-cored moraines at the glacier margin. They could also have been melted out over the existing lateral moraine which would create the illusion that the moraine is higher. Since the deposits are above the ELA they are not made as a result of sediments following the flow lines of the glacier and consequently can’t be characterized as lateral moraines.