308 CONTORTED DRIFT OF IVREA. chap. xv. 



successive phases of glacial action in Switzerland, to which I 

 shall presently advert. 



Contorted Strata of Glacial Drift south of Ivrea. 



At Mazze, near Caluso (see map, p. 306), the southern ex- 

 tremity of this great moraine has recently been cut through 

 in making a tunnel for the railway which runs from Turin 

 to Ivrea. In the fine section thus exposed, Signor Gastaldi 

 and I had an opportunity of observing the internal structure 

 of the glacial formation. In close juxta-position to a great 

 mass of till with striated boulders, we saw stratified beds of 

 alternating gravel, sand, and loam, which were so sharply 

 bent that many of them had been twice pierced through in 

 the same vertical cutting. Whether they had been thus 

 folded by the mechanical power of an advancing glacier, 

 which had pushed before it a heap of stratified matter, as the 

 glacier of Zerniatt has been sometimes known to shove for- 

 ward blocks of stone through the walls of houses, or whether 

 the melting of masses of ice, once interstratified with sand 

 and gravel, had given rise to flexures, in the manner before 

 suggested, pp. 138 and 220, it is at least satisfactory to have 

 detected this new proof of a close connection between ice- 

 action and contorted stratification, such as has been described 

 as so common in the Norfolk cliff's, p. 221, and which is also 

 ver}^ often seen in Scotland and North America, where strati- 

 fied gravel overlies till. I have little doubt that if the marine 

 pliocene strata, which underlie a great part of the moraine 

 below Ivrea, were exposed to view in a vertical section, those 

 fundamental strata would be found not to participate in the 

 least degree in the plications of the sands and gravels of the 

 overlying glacial drift. 



To return to the marks of glaciation : in the moraine at 

 Mazze, there are many large blocks of protogene, and large 



