AbstractThe slopes of Vestfonna, which is a relatively small (7895 km2) dome-shaped icecap, are in this paper divided into two parts, one above the equilibrium line, where ice layers form in the snow pack and the other below the equilibrium line, where superimposed ice forms and ablation occurs.The main study of the formation of ice layers in the snow pack was carried out on the summit of Vestfonna, at Ahlmann Station (elevation 622 m). Thin ice layers in the uppermost part of the snow formed at the beginning of the melt season, when the snow was still cold and only a small amount of melt water had percolated downwards. The thickness of ice layers was found to increase with depth.Within the zone of superimposed ice measurements were made of crystal sizes in the ice layers. During the formation of these ice layers their grain sizes were recorded. Results of the crystallographic studies indicated that crystals in separate ice layers were small, whereas large crystals were found to form generally during warm summers.