MEMOIR OF GUYOT. 699 



the extremity of the jj^lacier. He gives a figure of the Rhone glacier 

 as seen from the Maienwancl in illustration, and other later glacial- 

 ists have appealed to the same evidence of lateral friction. 



Tlie semicircular outline of the terminal moraine was found to be 

 another result of the cause just mentioned; and so also the "even- 

 tail" arrangement of the several moraines immediately above the ter- 

 mination. The greater height and breadth of the central moraine is 

 made a consequence of the greater velocity of the ice at the middle 

 of the upper surfcice, more transportation taking place consequently in 

 a given time. 



Again : The conclusion that the movement of the glacier icas largely 

 through molecular displacement was supported by his observation that 

 the ice, instead of breaking up and rising into an accumulation of 

 masses on its passage by an isolated rock, or rocky islet, in its course, 

 spread around and enveloped it without fracturing ; .and he refers to 

 a fine example of this at the two isolated islets of rock in the midst 

 of the great Brenva glacier, called the " e-yes of the glacier." The 

 same thing is observed " at the Jardin du Talefre, a true islet in the 

 midst of a mer de glace, having a border of blocks of rock, or of a 

 moraine, cast upon its sides by the march of the glacier, just like the 

 coast dunes of an island in the ocean." 



In view of such fects, Guyot observes: " If it is true that the differ- 

 ent parts of a glacier move with different velocities ; if the glacier 

 adapts itself to the form of a valley and fills all depressions without 

 ceasing to be continuous ; if it can bend around an obstacle and closely 

 inclose it without the fracturing of its mass, like a spreading liquid, 

 we may afiirm that the movements take place through a molecular dis- 

 placement, and we must abandon, at least as the only cause, the idea 

 of a slow sliding of the mass upon itself as incompatible with the phe- 

 nomena presented."* 



The " blue bands " of the glacier were first described by Guyot. He 

 called the structure stratification, and observed it in the ice of the sum- 

 mit of the glacier of Gries, at a height of about 7,500 feet. A peculiar 

 furrowing of the surface of the ice, the furrows 1 or 2 inches broad, at- 

 tracted his attention ; and this result of weathering he found to have 

 come from the unequal firmness of the layers constituting it, layers of 

 a softer " snowy ice " alternating with those of firm bluish glassy ice. 

 The stratification was found by him to extend over hundreds of square 

 meters, and downward, on the sides of crevasses, 20 to 30 feet deep, or 

 as far down as the eye could penetrate 5 and it was evident that " the 

 layers of the two sides of a crevasse were once continuous, like the 



* In French his words of 1838 are : " On pent affirraer que ces nionvemeuts ne 

 penvent avoir lien qn'en vertu d'nn d<;placement moMcnlairo, et il faut abandonner, 

 an moius comnie canse nniqne, rid6e d'liu glissenient lent do la masse sur elle- 

 mfime, comme incompatible avec les ph^uom&ues quo pr<5dente la marche des gla- 

 ciers," 



