Niles.] . 382 [March 20, 



column. 1 I also observed many other examples of the same kind, 

 though none so regularly and beautifully perfect. 



There was there at that time another highly interesting and instruc- 

 tive exhibition of glacial action. Within a few feet of the down-stream 

 end of one of these elongated roches moutonnees and upon its crest, 

 there was a boulder fully three feet in diameter, which evidently had 

 been slowly moving along this ridge for some distance, probably from 

 its upper end. There were two sides of this block of stone which 

 were not incased in ice, viz., the lower one resting upon the rock, 

 and the one facing down the glacier. From the lower end of the 

 ridge of rock I looked at the boulder through a tunnel of pure, blue 

 ice, which was continued as a deep furrow in the under surface of 

 the glacier for fully thirty feet from its beginning. As this was pro- 

 duced by the ice moving over and beyond the boulder, it was evident 

 that the ice was moving more rapidly than the stone. I afterwards 

 found other examples of the same kind, but none so favorably situated 

 for a striking exhibition of this property of ice. It will be understood 

 that these stones were sufficiently below the upper surface of the 

 glacier to be removed from the effects of the ordinary changes in the 

 temperature of the atmosphere. Although stones which are exposed 

 to such changes may be frozen into the ice at the edges of the gla- 

 ciers, yet I believe these were so situated as to correctly represent 

 the conditions and movements of those at still greater depths. If 

 this is correct, and I believe it is, it follows that such fragments of 

 rock are not rigidly held in fixed positions in the under surfaces of 

 glaciers and carried irresistibly along at the same rate, but that the 

 constantly melting ice actually flows over them, and that their motion 

 is one of extreme slowness, even when comparedVith the motion of 

 the glacier itself. 2 



2 I see by quotations from the "Nouvelles Excursions et S6jours dans les Gla- 

 ciers etles hautes regions des Alpes," by Prof. E. Desor, that he there described 

 similar features which he observed in connection with the Aar Glacier in 1844, but 

 I have not been able to obtain a copy of the work for examination. 



2 In an article in The Geological Magazine, Decade II, Vol. in, 1876, published 

 during the same season that I was making these observations, and which I had not 

 then seen, being away from home, Rev. T. G. Bonney clearly states the same con- 

 clusion, presenting as evidences the appearances of certain boulders observed by 

 him in 1875, near the terminations of the Glacier des Bois and the Glacier d'Ar- 

 gentiere. 1 do not learn from what he has written, however, that he saw the 

 ice flowing over stones in the manner I have here described. It is, therefore, my 

 pleasure to have witnessed what I consider to be a proof of the accuracy of the 

 conclusion which Prof. Bonney ably drew from other sources. 



