310 iieport of the Researches (f M. Agassiz, 



the middle of the glacier, at the biise of the cascade, and that 

 this pressure, by forcing forward the concentric arcs, pro- 

 duces the appearance of curves which exists ; and because the 

 crevices are at right angles with the arched lines, he concludes 

 that they are the blue bands. Unquestionably, it is a fact, 

 speaking generally, that the blue bands intersect the crevices 

 at right angles, and we willingly concede that Professor Forbes 

 was the first who pointed out the circumstance to the attention 

 of observers ; but surely this is insufficient ground for the in- 

 ference, that all the lines or outlines which exhibit this pecu- 

 liarity are consequently blue bands. We have a thorough 

 conviction, that if Professor Forbes, instead of confiding in 

 the infallibility of this rule, had more narrowly examined the 

 structure of these concentric arches, he would have been satis- 

 fied that they do not at all correspond to the primitive blue 

 bands (his ribboned structure) ; that these latter are much few^er, 

 and that where they exist they do not coincide with the arched 

 lines of the surface, which are so readily distinguished higher 

 up, at Meyenmand. I believe, that, with a closer attention to 

 facts, we might give a more natural account of all the pheno- 

 mena. In truth, to every one who notices the arrangement 

 of the strata in a glacier, it is evident that these concentric 

 lines which Professor Forbes regards as blue bands, are no- 

 thing else than the outcroppings of the strata. Now, if we 

 admit that the cascade dislocates the glacier only at the sur- 

 face, there is nothing astonishing in finding that it produces 

 beneath the same arrangement of strata which prevailed above . 

 The only peculiarity which presents any difficulties is the fact, 

 that the arched lines are almost transversal at the foot of the 

 cascade, whilst farther down they form curves which are more 

 and more prolonged. It is as if the glacier was again re-formed 

 after it had passed the fall. Perhaps, also, the strata are but 

 little arched immediately above the cascade, and in that case 

 there would be nothing astonishing that their outlines corre- 

 sponded beneath also. The whole difficulty, then, comes to 

 this : Does the cascade break up the glacier throughout its 

 whole depth, or is the whole phenomenon confined to the sur- 

 face \ The examination of the strata at the upper part of the 

 glacier can alone solve this problem. 



