148 THE FOKMS OF WATER Itf 



de Grlace, and we now know that, unless they are split 

 and shattered by the frost, these rocks will, at some 

 distant day, be landed bodily by the Glacier des Bois 

 in the valley of Chamouni. You have already learned 

 that these boulders often reveal the mineralogical nature 

 of the mountains among which the glacier has passed; 

 that specimens are thus brought down of a character 

 totally different from the rocks among which they are 

 finally landed; this is strikingly the case with the 

 erratic blocks stranded along the Jura. 



369. For the Jura itself, as already stated, is lime- 

 stone ; there is no trace of native granite to be found 

 amongst these hills. Still along the breast of the 

 mountain above the town of Neufchatel, and at about 

 800 feet above the lake of Neufchatel, we find stranded 

 a belt of granite boulders from Mont Blanc. And when 

 we clear the soil away from the adjacent mountain side, 

 we find upon the limestone rocks the scarrings of the 

 ancient glacier which brought the boulders here. 



370. The most famous of these rocks, called the 

 Pierre a Bot, measures 50 feet in length, 40 in height, 

 and 20 in width. Multiplying these three numbers 

 together, we obtain 40,000 cubic feet as the volume of 

 the boulder. 



371. But this is small compared to some of the 

 rocks which constitute the freight of even recent 

 glaciers. Let us visit another of them. We have 

 already been to Stalden, where the valley divides into 



