Page:Popular Science Monthly Volume 14.djvu/105

Rh de Miage, with its wild and ruffled surface breaking in cataracts of splendor down its steep defile, by its unceasing attrition upon the mountainside, and its perpetual transport of bowlders, has piled up, far out in the valley it occupies, a long and high slope of gravel and rocks, whose impervious sides dammed up the allée blanche and formed Lac Combal. So immense became the accumulations of débris that they consolidated into an impregnable hill, around whose base the glacier poured its divided stream. The Glacier la Brenna in 1767 was much contracted, while in 1831 new accretions caused it to reach out and attack with such vigor a promontory in its path as to shatter it with fissures, and compel the removal of a chapel upon its crest. Upon this same glacier Principal Forbes has observed the very act of glaciation, its method and effects. One side of the ice was exposed and found by him thickly set with nodules, pieces of granite as large as cherries, and protuberances of stone, while beneath this armed surface lay the limestone, over which it had just passed, with its face finely lined and graven in the direction of the glacier's motion. This glacier, now shrunken from its former imposing magnitude, once erected below its present terminus moraines of enormous size, while in its retreat it paved the land, predestined to sterility, with thickly-scattered fragments. On the west bank of the Mer de Glace, two hundred and forty feet above the present level of the glacial débris, traveled rocks lie in morainic alignments, and the bed-rock is scratched and abraded, indicating an ancient margin of the glacier in days when its frigid tide was swollen by greater additions and more favorable climates.

The distinction between aqueous action upon the rocks and mechanical abrasion is easily understood, and their presence readily distinguished. Forbes observed a face of limestone marked with grooves many yards in length, and, nearly horizontal above them, he found the marks produced by flowing water charged with fragments. The latter were blunt, irregular, and blotchy, having no continuity, and strikingly contrasted with the straight rulings below them. Furthermore, the memorable flood of water which devastated the valley of Bagnes, a mass over five hundred million cubic feet in volume, which swept up bridges and houses, snapped trees asunder, and transplanted a colony of buildings, was yet unable with all its Titanic violence to move large bowlders which it encountered even through inconsiderable distances.

In our glance over the glacial fields of to-day, leaving the inferences from those facts mentioned to be drawn themselves, let us briefly inspect the frozen valleys and important ice-streams of Norway. The backbone of the Scandinavian peninsula lies in Norway, reaching from Drontheim to the North Cape in the long neck of the Kiölen Mountains. This chain attains in places an elevation of six thousand feet, and again stoops to less than two thousand, receding at times from the shore-line, and again pushing out upon the ocean, till, as in the Loffoden Islands, many of its conspicuous summits stand insulated among its billows.