Nischbildningsprocesser : en fältstudie vid Passglaciären, Kebnekaise

In this study, physical properties of a small glacier in Kebnekaise Mountains, northern Sweden, are investigated in order to evaluate its erosionai capacity. By definition, glacial cirques are cut out by erosion by cirque glaciers. In areas characterized by low precipitation and pemafrost, small glaciers have very low erosional capacity. Is it possible that a small glacier can excavate a cirque form during such conditions? According to the investigations, it is unlikely that the cirque mainly has been developed by erosion by a cirque glacier. It is prooved that the cirque has been a part of a powerful valley glacier. When the cirque is a part of the accumulation area to a bigger glacier, conditions for erosion are much improved. The erosion of the cirque must have been more intense during periods when the valley glacier existed. The selected glacier is nearly as big as it can be, still classified as a cirque glacier. When the bottom topography is reconstructed, a distinct cirque form appears. Studies of ice-thickness, temperature profile, ice-velocity, mass turnover and glacial morphology shows that the major part of the glacier is frozen to the bed. Erosion is restricted to a limited area. Based upon climatic and glaciological history, the total time during Quaternary when the glacier might have existed is estimated. The maximum time of erosion seems short. It's concluded that probably several processes are acting when a cirque is formed, and erosion by cirque glaciers is not necessarily the main process. Thus, the definition of glacial cirques is herein suggested to be less specific with respect to the genetic process.