182 Notice of Prof. Forbes' 's Travels in the Alps. 



the character of a colossal backbone of the glacier, or sometimes ap- 

 pears like a noble causeway, fit indeed for giants, stretching for leagues 

 over monotonous ice, with a breadth of some hundreds of feet, and 

 raised from fifty to eighty feet above the general level. Almost every 

 stone, however, rests on ice ; — the mound is not a mound of debris, as 

 it might at first appear to be. Nor is this all. Some block of greater 

 size than its neighbors, covering a considerable surface of the ice, be- 

 comes detached from them, and seems shot up upon an icy pedestal. 

 This apparent tendency of the ice to rise wherever it is covered by a 

 stone of any size, results from the fact, that its surface is depressed 

 every where else by the melting action of the sun and rain, — the block 

 like an umbrella protects it from both, — its elevation measures the level 

 of the glacier at a former period, and as the depression of surface is 

 very rapid — amounting to a foot per week during the warm months of 

 summer — the ice, like the fields, puts forth its mushrooms, which ex- 

 pand under the influence of the warm showers, until the cap becoming 

 too heavy for the stalk, or the centre of gravity of the block ceasing to 

 be supported, the slab begins to slide, and falling on the surface of the 

 glacier, it defends a new space of ice, and forthwith begins to mount 

 afresh. These appearances are called Glacier Tables, and their origin 

 was perfectly explained by Saussure." 



Sand washed into the hollows, eventually forms a protection from 

 farther melting, and the hollows, by the melting of the surrounding ice, 

 form cones of great regularity, twenty or thirty feet high, and eighty 

 or one hundred in circumference. 



The snow as regularly disappears and melts from the surface of the 

 glacier, as it does from the surface of the ground in its neighborhood ; 

 but it disappears more tardily as we ascend, and at length we reach 

 a point where it never disappears at all, and this is the snow line upon 

 the glacier. The term neve, used by modern glacialists, means that 

 part of the glacier which is covered with perpetual snow ; it is where 

 the surface of the glacier begins to be annually renewed by the un- 

 melted accumulation of each winter, and the stratification is entirely 

 obliterated as the neve passes into complete ice. 



The icebergs of the polar seas are chiefly neve, or consolidated 

 snow. It is far more easily fractured than ice, and also more easily 

 thawed and water-worn, " hence the caverns in the neve are extensive 

 and fantastical, often extending to a great distance under a deceptive 

 covering of even snow, which may lure the unwary traveller to de- 

 struction. Sometimes through a narrow slit or hole opening to the 

 surface of the neve, he may see spacious caverns of wide dimensions, 

 over which he has been ignorantly treading, filled with piles of de- 

 tached ice-blocks, tossed in chaotic heaps, whilst watery stalactites — 



