OF THE ALPS, NORTH ITALY. 863 
the moraine profonde covered up, protected, and preserved the small 
remnants of the marine beds which remain to tell so much of past 
conditions here. 
Again, ascending to the top of La Serra, the grand left lateral 
moraine, and crossing its great breadth of four miles to Monte 
Grando on the Biella road, directly we pass off the area where 
glacial action has been excessive, the Pliocene formation is again 
met with in this more sheltered corner. 
It is difficult to say to what thickness the Pliocene had attained 
before the final elevation to its present altitude, and it may once 
have been higher; it had a great horizontal extension at the south 
base of the Alps, and there has been an enormous destruction of 
these beds, chiefly during the Glacial period. I believe that the 
Pliocene sea extended far up the main valleys in fiord-like arms ; 
and it is not surprising that all deposits of this age have been so 
completely and cleanly swept out of these valleys, so that, with the 
exception of the remnant on the Lago d’Orta, not a vestige remains. 
Within the valleys glacial denudation, when at its maximum, must 
have been more rapid and complete than on the southern face of the 
mountains; and yet even here for miles there is no trace of these 
deposits. ' 
I trust that in bringing these sections to your notice I have been 
able to show how the existing portions have been preserved, and 
what is their relative position to the present valleys and lake- 
basins. 
At Arona, where I spent some days exploring the country on 
both sides the Lago Maggiore, I was fortunate enough to find, near 
the village of Dormiletto, traces of marine conditions. ‘This village, 
situated on the south-west extremity of the lake, stands ou a 
plateau about 100 feet above it (112 feet by aneroid), and close 
under the moraine which rises immediately to the west. This 
moraine is much intersected by narrow ravines, showing on their 
sides fine. sections of the moraine profonde, and the surface moraine 
on the top. ; 
In the bed of such a ravine close to Dormiletto fossils were 
found in a patch of fine white gritty marl, showing up through the 
subangular débris. Its position in situ I never determined quite to 
my satisfaction, so small a portion being uncovered; and I had no 
means of excavating for any distance and removing the gravel and 
blocks of stone which covered it. It was in the very lowest and 
narrowest part of the ravine, just where it opened on to the plateau, 
so that nothing below this level can be seen in any direction. If 
this is a large detached block buried in the ravine, then it must 
either have been derived from the cliffs at the head or on the side 
of the ravine, or it has been washed out of the moraine material. 
After very close search, I could discover no bed similar to it in 
the ravine above, nor any blocks of similar material in the glacial 
sands and clays. In either case it is interesting; if it is in situ, 
we have proof of marine conditions here; if transported, it must be 
a portion of beds not far distant, situated at a higher level to the 
