208 PHYSICAL GEOGRAPHY. 



Saussure, " a spectator could be placed at a sufficient height above the Alps, to embrace 

 at one view those of Switzerland, Savoy, and Dauphine, he would see a mass of mountains 

 intersected by numerous valleys, and composed of several parallel chains, the highest in 

 the middle, and the others decreasing gradually as they recede. The central and highest 

 chain would appear to him bristled with craggy rocks, covered, even in summer, with 

 snow and ice in all those places that are not absolutely vertical ; but on both sides of the 

 chain, he would see deep and verdant valleys, well watered and covered with villages. 

 Examining still more in detail, he would remark that the central range is composed of 

 lofty peaks and smaller chains, covered with snow on their tops, but havin"- all their 

 slopes that are not very much inclined, covered with ice, while the intervals between 

 them form elevated valleys filled with immense masses of ice, extending down into the 

 deep and inhabited valleys which border on the great chain. The chain nearest to the 

 centre would present to the observer the same phenomenon, but on a smaller scale, 

 beyond which he would see no more ice, nor even snow, save here and there on some of 

 the more elevated summits." Saussure therefore recognised two kinds of glaciers ; the 

 first contained in the valleys, more or less deep, and which, though at great elevations, 

 are still commanded on all sides by mountains higher still $ the second not contained in 

 valleys, but spread out on the slopes of the higher peaks. 



The glacier system of the Alps embraces an extensive area. M. Ebel estimates, that 

 there may be at least four hundred of the larger sized glaciers, or varying from three to 

 thirty miles in length. The aggregate superficial extent of all those of the Tyrol, 

 Switzerland, Piedmont, and Savoy, is calculated by some authorities to amount to not 

 less than fourteen hundred square miles. The greatest breadth of an individual specimen 

 is seldom more than two miles. The thickness varies from a hundred to six hundred 

 feet. The glaciers are moving masses, urged down the inclined planes upon which 

 they are situate by the mutual pressure of their parts, a movement which the seasons 

 accelerate or retard according to their character. This motion gives rise to the 

 extraordinary spectacle, of summer productions and winter formations being sometimes 

 in immediate contact with each other, the ice-fields obtruding into flowery meadows, and 

 gradually forcing their way into the regions of cultivation. According to Professor 

 Forbes, the very huts of the peasantry are sometimes invaded by this moving ice, and 

 many persons now living have seen the full ears of corn touching the glacier, or gathered 

 ripe cherries from the trees with one foot standing on the ice ! The rate of advance of 

 different glaciers varies considerably. M. Ebel states, that in the valley of Chamouni, 

 they travel at about fourteen feet a year, while in that of Grindelwald, the glaciers move 

 rather faster, at the rate of twenty-five feet in a yeai-, a difference probably attributable 

 to the ground being variously inclined. The same glacier will also make more progress 

 in one year than in another, according as a summer of lesser or greater warmth renders 

 its liberation more or less complete. Captain Hall remarks upon the ploughing up of the 

 ground lying before a glacier by its snout as an obvious proof of its progression, and 

 instances the remarkable case of the glacier of Brenva falling into the lower part of the 

 Alice Blanche, fairly crossing from one side of the valley to the other, and being so 

 irresistibly pressed forward by the weight of snow on its shoulders, high up the sides of 

 Mont Blanc, that on reaching the opposite side of the valley, it actually travels for a 

 considerable distance up the bank. " The guides," he remarks, " pointed out the corners 

 of green fields, peeping out from the sides of the glacier in the middle of the valley, 

 and showed us traces of walls and fences which had belonged to large villages, now entirely 

 obliterated by the moving mass. I took notice of one circumstance, which told the 

 fa- al story very well. We had walked along a well-worn footpath till our course was 

 ab aptly stopped by the edge of the glacier ; but on crossing over it, we re-discovered 



