Arnold Guyot. 365 



sioDs without ceasing to be continuous ; if it can bend around 

 an obstacle and closely enclose it without the fracturing of its 

 mass like a spreading liquid, we may affirm that the move- 

 ments take place through a molecular displacement, 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 summit of the glacier of Grries, at a height of about 7500 

 feet. A peculiar furrowing of the surface of the ice, the fur- 

 rows one or two inches broad, attracted 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 ; and it 

 was evident that the layers of the two sides of a crevasse were 

 once continuous, "like the strata of the opposite sides of a 

 transverse valley." He compared the stratification to that of 

 certain coarsely schistose limestones. f He remarks in conclu- 

 sion : " We should say that the layers were not annual layers, 

 but rather a series made day by day from small successive 

 snow-falls that were melted in part by the sun of the day, and 

 covered each night by the thick frost-glazing which envelops all 

 the snowy summits of the high Alps.";}: 



He further observes that "these beds were evidently formed 

 at a greater height and in a different position from that where 

 observed." He adds, in closing his remarks on the subject — 

 " Do the beds, at first horizontal, or at least parallel to the 

 surface of the glacier, accomplish, during its movement, evolu- 

 tions, as yet imperfectly understood, analogous to those before 

 mentioned [that is, those occasioned by differences in velocity 

 of the middle, sides and bottom, owing to unequal friction]. 

 This is a point whieh should have further examination, with 

 observations as minute, numerous and universal as possible. 

 Unfortunately a thick fog and threatening weather forced me 



* In French his words of 1838 are: "On peut affirmer que ces mouvements ne 

 peuvent avoir lieu qu'en vertu d'un deplacement moleculaire, et il faut abandonner, 

 au moms comme cause unique, l'idee d'un glissement lent de la masse sur elle-meme, 

 comme incompatible avec les phenomenes que presente la marche des glaciers." 



f His words are : " stratifie a la facon de certains calcaires grossierenient schis- 

 teux ;" and lie explains it himself as implying a lamellar structure. ,~s^=j 



\ In the original, the words are : On aurait dit, non pas des couches annuelles, 

 mais une serie de couches plutot journalieres de neige tombee successivement par 

 petites quantites. puis fondue en partie par le soleil de la journee, et couverte 

 chaque nuit de cet epais verglas qui, au-dessus de la region des glaces, recouvre 

 toutes les sommites neigeuses des hautes Alpes." 



