Page:Popular Science Monthly Volume 7.djvu/476

460 results of observations upon the glaciers which they enjoy such remarkable facilities for examining. About 175 miles in a direct line to the northwest of Christiania (which is not only the capital of Norway, but the seat of one of the best universities of Europe) is a spur of the principal range included between the two inlets of Sogne and Nord—fiords. Upon its top is the largest snow-field of Norway, which bears the name of Justedal (Jostedalsbræen). Its superior magnitude and its comparative nearness to Christiania have led to its selection by two of the most eminent geologists of the country as a subject of special study. In 1869 Prof. Sexe published, as the "Programme" of the university for the first semester of the preceding year, a paper on the great glacier of Boium; and, in 1870, M. C. de Seue, of the Meteorological Institute, gave to the world, as the "Programme" for the second semester of that year, a more extended account of his observations under the title of "Le Névé de Justedal et ses Glaciers." Some of the results of the researches of these gentlemen may be of interest even to those who would soon grow weary of purely scientific details.

This immense field of snow and ice measures over forty miles in length from northeast to southwest, and from four to seven miles or more in breadth, covering, with its dependencies, according to M. de Seue's calculations, not less than some 550 square miles. The névé, or snow-field proper, is by no means a dead level, but the inequalities of the rocky crags are, for the most part, concealed by the thick deposit of snow, which is supposed to be at least 150 feet deep on the average, while in places it certainly fills up depressions of twice that depth. Here the snow is granular, lying in distinct layers, the product of the storms of successive seasons, and rent with frequent fissures. The glaciers spring from the edge. Wherever the jagged cliffs with which that edge bristles fall away and leave ravines, there the snow-field seeks an outlet. The glaciers are, as it were, the rills by which the great perennial reservoir discharges into the valleys below. So numerous are they, that their exact number has never been ascertained. Of glaciers of the first class, or those which pour their icy streams quite down into the valley, there are twenty-four; but, if we also include in the enumeration the glaciers of the second class, or those which remain suspended on the mountain-sides, the number is counted by hundreds. Some of the second class, it may be noticed, seem almost entitled, by reason of their breadth and depth, to be included in the higher class.

Each glacier presents many of the same phenomena as all the rest. From the moment it leaves the parent névé, or snow-field, the constitution of the mass is different from that of recently-fallen snow. Compressed by the immense weight of the superior strata, that lower portion of the névé which feeds the glacier is, at the very start, transformed into a solid ice, whose particles are cemented by the alternate