Géomorphologie et Glaciologie en Islande centrale

Résumé En

English summary The authors, thanks to a generous grant from the « Centre National de la Recherche Scientifique » (The French National Center for Scientific Research), were enabled to stay in the very heart of Iceland during the summer of 1954. Their basis, indeed, was located at 65° 02' N lat, and 18° 18' E long. Greenwich, about 19 km from Hofsjokull, an ice-cap covering nearly 1030 km2. The authors, having first contributed some further details to our knowledge of the structure of the large pre-Villafranchian basalt table-lands which make up the whole northern part of the island, proceed to examine the climate of the environs of Hofsjokull and the present morphogenesis associated with it, and, lastly, the ice-cap itself. The climate is characterized mostly by the surprising uniformity of temperatures which, during the summer, almost always range from 0° to 10° G at a height of about 800 m. Permafrost was noticed to be non-continuous, and to exist in hollows only. The main processes noticed are an intense frost-shattering of certain basalts, and a number of beautiful rock- glaciers. About the glacier itself, the main points are that alimentation is probably 1 m to 1,5 m near the summit, while gross ablation is up to 5 cm per day during the warmest days. The distribution of altitudes, studied according to AHLMANN's method, leads us not to see in Hofsjokull a micro-inlandsice. To sum up, the central Icelandic glacier is more related to Alpine glaciers than could be expected on a priori grounds, a conclusion rather similar to those reached by other recent missions to Valnajökull itself.