356 THE GREAT ICE AGE 



lower eminences of the Dome and Aiguille de Goiite, which 

 rise from a broad and uneven plateau of neve or hard snow, 

 sending down to the plain two great glaciers or streams of ice, 

 the Bossons and Tacony glaciers. Eastward of Mont Blanc 

 the neve or snow plateau is penetrated by a series of sharp 

 points of rock or aiguilles, which stretch along in a row of 

 serried peaks, and then give place to a deep notch, through 

 which flows the greatest of all the glaciers of this side of Mont 

 Blanc, the celebrated Mer de Glace, directly in front of our 

 standpoint. To the left of this is another mass of aiguilles, 

 culminating in the Aiguille Verte. This second group of 

 needles descends into the long and narrow Glacier of Argen- 

 tiere, and beyond this we see in the distance the Glacier and 

 Aiguille de Tour. As seen from this point, it is evident that 

 the whole system of the Mont Blanc glaciers originates in a 

 vast mantle of snow capping the ridge of the chain, and extend- 

 ing about twenty miles in length, with a breadth of about five 

 miles. This mass of snow being above the limits of perpetual 

 frost, would go on increasing from year to year, except so far 

 as it might be diminished by the fall of avalanches from its 

 sides, were it not that its plasticity is sufficient to enable the 

 frozen mass to glide slowly down the valleys, changing in its 

 progress into an icy stream, which, descending to the plain, 

 melts at its base and discharges itself in a torrent of white 

 muddy water. The Mont Blanc chain sends forth about a 

 dozen of large glaciers of this kind, besides many smaller ones. 

 Crossing the valley of Chamouni, and ascending the Montan- 

 vert to a height of about 6,000 feet, let us look more particu- 

 larly at one of these glaciers, the Mer de Glace. It is a long 

 valley with steep sides, about half a mile wide, and filled with 

 ice, which presents a general level or slightly inclined surface, 

 traversed with innumerable transverse cracks or crevasses, 

 penetrating apparently to the bottom of the glacier, and with 

 slippery sloping edges of moist ice threatening at every step to 



