The first section of the new 1: 10,000 map of the Aletsch Glacier, an I.G.Y. project, was published about a year ago and was reviewed in the Journal of Glaciology, Vol. 3, No. 30, 1961, p. 1160. This was Sheet 3 covering the lowest part of the glacier from the Märjelensee to the snout.
Sheet 2 has now been published. It shows the middle part of the glacier between the Konkordiaplatz and the Märjelensee, an area which has been studied intensively, particularly by the Abteilung für Hydrologie der Versuchsanstalt für Wasser- und Erdbau an der Eidg. Technischen Hochschule in Zürich.
The major feature of the map is the Konkordiaplatz. Of the four major ice streams which meet there, the map shows the lower parts of the Grosser Aletschfirn to the west and the Grüneggfirn to the east; the Jungfraufirn and the Ewigschneefeld appear on the northern edge of the map. Moraines are shown, and all of the well-defined dirt features and crevasses. The two moraines bordering the Jungfraufirn at the top of the map are 900 m. apart; after having traversed Konkordiaplatz they approach each other as close as 170 m. As it narrows the Jungfraufirn also deepens, and at the Konkordiaplatz the ice has a seismically determined depth of some 800 m.—the greatest thickness yet recorded on an Alpine glacier.
At the Konkordiaplatz the four ice streams combine to form the main glacier, and this then flows over a rock step between the Dreieckhorn and the Faulberg. The glacier reaches its maximum velocity of 200 m./yr. in this narrow and steep area. Here the net ablation amounts to 2–3 m./yr., and near the snout this figure increases to 12–15 m./yr.
Sheet 2 also covers almost the whole basin of the Mittelaletschgletscher to the southwest. This glacier has shrunk so much that it no longer contributes ice to the main glacier, and the map shows that its surface now lies above that of the main glacier.
An interesting feature of the map is the recording in certain parts of it, by means of coloured lines, of the probable ice extent at earlier periods of time.
Work on the outstanding Sheets 1, 4a and 4b of the Aletsch Glacier map is in progress. It is expected that the complete 1 : 10,000 map of the whole Aletsch basin will be published in 1963.
