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 

 extremity 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 

 Grastaldi and I had an opportunity of observing the internal 

 structure of the glacial formation. In close juxtaposition 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 Zermatt has been sometimes known to shove 

 forward 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 cliffs, p. 222, and 

 which is also very often seen in Scotland and North America, 

 where stratified 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 



