LYELL. 341 



a stronger or more satisfactory case. But in the 

 same paper the authors hazarded an opinion that 

 although the old Alpine moraines stopped short 

 after going a few leagues from the Alps, yet at 

 some former time erratics had been conveyed to 

 the summit of the Collina, just as " Pierre a Bot " 

 and other blocks had been carried by the old Rhone 

 glacier to the flanks of the Jura. Now when I 

 read this at Zurich, I immediately recollected that 

 in the valley of the Bormida, when I passed from 

 Savona to Alessandria in 1828, 1 had been astonished 

 at some very huge erratics of serpentine in the 

 Miocene. Having never seen blocks of such enor- 

 mous dimensions in any tertiary formation, I was 

 relieved in 1828 at finding, in some spots on the 

 Bormida, projecting fragments of serpentine in places 

 which the erosion of the valleys had exposed to 

 view. I concluded that they may not have travelled 

 far, and when I saw some large blocks on the 

 Superga (in 1828), I immediately suspected that as 

 that hill consisted of beds of the same formation, 

 the blocks might have been washed out of the 

 Miocene not far off. I therefore now suggested 

 this view to Gastaldi, and found that he was by no 

 means tenacious of his printed theory, although 

 he said that the blocks were many of them angular, 

 of very great size, and accompanied by Alpine 

 loam. We then examined the beds of the Superga, 

 both those dipping to the north-west, and those to 

 the south-east, and on both sides of this anticlinal 

 are strata containing fragments of stone of various 



z 3 



