Conversion of Neve into Ice. 147 



the letter r of the word ** Glacier *' on the eye-sketch of a 

 ground plan of the glacier in my published volume. From 

 tlie 7th to the 10th August, I found the daih; motion to be 

 09 inches ; or the very same as that just given for the Glacier 

 de Nant Blanc, than whicli, two cannot be more dissimilar. 

 But the smallness of the motion in the latter case, is due to 

 the great height and very small neve or reservoir ; in the 

 former, to the exceedingly slight declivity and enormous fron- 

 tal resistance to the exit of the glacier into the Allee Blanche, 

 already encumbered with its ponderous mass and debris. 



Whilst speaking of the Glacier de Miage, I may add, that 

 I found on the most westerly of the medial moraines, dark 

 blue lias-schist, which undoubtedly comes from the very axis 

 of this granitic chain, where it has not hitherto been suspected 

 to exist. Also, that a repeated examination of the curious 

 *' ancient moraines," forming semicircular embankments to- 

 wards the Lake of Combal, described in my Travels, p. 194, 

 and figured in the eye-sketch, has convinced me that these 

 cannot be of so old a date as I then believed ; but are due to 

 a temporary outbreak of the glacier at some not very remote 

 period, when the accumulation of pressure of the ice has been 

 such, that an overflow took place laterally, which deposited 

 these moraines in succession as it retired, and the glacier 

 retreated to its present limit. I found an exactly analogous 

 case in the Glacier des Bois, at Chamouni ; which, at some 

 period not on record, has thrown out an arm between the 

 Chapeau and the Cote du Piget. 



Having fully described the measures of the Glacier of La 

 Brenva in my last letter, I shall not here return to them. 



Thus I have been able to add the velocity of four additional 

 glaciers to the small number previously ascertained. 



(2.) ON THE CONVERSION OF THE TS'kwt INTO ICE. 



I shall now add a few observations tending to throw light 

 on two of the most obscure glacial phenomena, first, the con- 

 version of the snow of the Neve into pure ice, and, secondly, 

 on the apparent ejection of stones from the surface of the 

 glacier. 



On the first point. I made some interesting observations 



