Presented by the Glaciers of Switzerland. 345 



navia, has been the same as that which produced them among 

 the Alps. In fact, the detailed descriptions and figures given 

 by M. Durocher, correspond so well to the furrowed surfaces 

 of our Alps, that I cannot perceive any important differences, 

 the contrast between the sides that have been abraded and the 

 sides that have been preserved, existing also among us, a cir- 

 cumstance of which M. Durocher himself mentions instances. 

 I likewise share with him the opinion, that the agents which 

 produced the furrows must have been flexible. M. Durocher 

 is of opinion, that, among the agents that have been proposed 

 to explain this phenomenon, water alone possesses this cha- 

 racter, and he, consequently rejects ice. It is worth while, 

 however, to examine whether the ice of glaciers is really des- 

 titute of the degree of flexibility necessary to produce this 

 efl'ect. 



Now, without taking into account the results obtained of 

 late years by Messrs Agassiz and Forbes, relative to the 

 movements of glaciers, results which cannot well be ex- 

 plained without attributing to the ice of glaciers the proper- 

 ty of bending and becoming flexible, I am persuaded, that, if 

 we observe the curves and folds described by the blue and 

 white bands (elsewhere rectilinear and parallel to the length 

 of the glacier) in the neighbourhood of rents, and, in general, 

 wherever the movement of the glacier has been interfered 

 with by some obstacle, no one can refuse to admit that the ice 

 of glaciers is flexible, and suj/iciently ^enihle to enter, under an 

 adequate pressure, into all the anfractuosities of the ground 

 and of the walls of glaciers : in short, that it is sufficiently flex- 

 ible to accommodate itself to all the movements M. Durocher 

 requires in the grooving agent. If the ice of glaciers is not 

 very flexible in certain circumstances, how can we explain the 

 very sharp folds, and the insensible passage to fainter curves, 

 represented in Figs. 1, 2, 3, 4, Plate III., — curves which, 

 as has been already stated, are never found but when cre- 

 vasses, more or less frequent, intimate that the glacier is in- 

 teri'upted in its movement, and has obstacles to overcome ? 

 I ought to add, that, in nature, the curves are much more 

 regular, and better marked, than they are in the figures. 

 They are also much nearer each other, the breadth of the 

 blue and white bands varying from nearly 1 millimetre to 4 



