THE ICE AGE. 



95 



de Miage, with its wild and ruffled surface breaking in cataracts of splen- 

 dor down its steep defile, by its unceasing attrition upon the mountain- 

 side, 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 im- 

 pervious sides dammed up the allee blanche and formed Lac Combal. 

 So immense became the accumulations of debris 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 nod- 

 ules, 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 gla- 

 cier'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 debris, 

 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 cli- 

 mates. 



The distinction between aqueous action upon the rocks and mechani- 

 cal abrasion is easily understood, and their presence readily distin- 

 guished. 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 build- 

 ings, 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 Kiolen 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. 



