Notice of Prof. Forbes' 's Travels in the Alps. 181 



raines, as they are called. The geology and mineralogy of inaccessi- 

 ble precipices, are thus learned by inspecting the masses that have cer- 

 tainly fallen from them." 



" A glacier is an endless scroll, a stream of time, upon whose stain- 

 less ground is engraved the succession of events, whose dates far trans- 

 cend the memory of living man." " Assuming roughly the length of a 

 glacier to be twenty miles, and its annual progression five hundred feet, 

 the block which is npw discharged from its surface in the terminal mo- 

 raine, may have started from its rocky origin in the reign of Charles I ! 

 The glacier history of two hundred years is revealed in the interval, 

 and a block larger than the largest of the Egyptian obelisks, which has 

 just commenced its march, will see out the course of six generations of 

 men ere its pilgrimage too be accomplished, and it is laid low in the 

 common grave of its predecessors." 



The mean or middle portion of the glacier, is a gently sloping tor- 

 rent, from half a mile to three miles wide — more or less undulating on 

 its surface, and more or less broken up by crevasses of a few inches to 

 many feet in width, and sometimes extending across the glacier, and to 

 a frightful depth.* They often impede, and sometimes arrest the trav- 

 eller, even when they appear trifling at a distance ; and they abound 

 with hollows, into which innumerable rills are precipitated, and com- 

 bine into large streams — thus establishing an extensive drainage, often 

 attended by bold and beautiful cascades. As the glaciers rise in win- 

 ter, they elevate the blocks of stone with them, and in consequence of 

 their sliding or rolling off laterally, they are often lodged on high 

 ledges, where they are left when the glacier sinks ; — they frequently 

 fall also over the sides of the glacier next to the rocky barrier, or they 

 are tilted into the crevasses and hollows, and by the motion of the icy 

 flood are ground and chafed, losing their angular form, and producing 

 grooves and scratches parallel to the motion of the ice. 



Two glacier streams sometimes unite and become confluent, and 

 each bearing along its line of rocks, two lines may thus combine into 

 one — producing medial or middle moraines composed of different ruins, 

 while the exterior line of each continues distinct. 



It is obvious that by the confluence of several glaciers, several mid- 

 dle moraines may be pi-oduced. " The moraines remain upon the sur- 

 face, and are rarely dissipated or engulphed ; on the contrary, the lar- 

 gest stones are set on a conspicuous preeminence — the heaviest mo- 

 raine, far from indenting the surface of the ice, or sinking among its 

 substance, rides upon an icy ridge as an excrescence, which gives to it 



* Nine hundred feet on Mont Blanc, as recently observed by Dr. Grant, an in- 

 telligent American traveller. — Eds. 



