| 860 H. H. GODWIN-AUSTEN ON TERTIARY FORMATIONS 
These boulders, although retaining their form and colour, are so 
completely disintegrated and softened that they can be sliced off in 
mass easily with the edge of the hammer. 
Higher up the winding ravine the dip changes to south, ata 
lower angle, and the beds rest against the porphyry, the lowest beds 
being gritty, with quartz pebbles and red ochraceous beds above. 
The Tertiary beds can be traced here and there below the bridge, 
but are there of a grey marly character, and only showing in the low 
banks as far as the high road from Boca towards the plains beyond. 
The village stands on the same formation, which here rises to about 
250 feet, west of the stream. I could find no fossils. 
Secrion AT Macerora. 
The next section of the Tertiary beds occurs at Maggiora, about 
a mile to the east, on the road to Borgomanero; and, owing to the 
formation of a new road descending towards the Sizzone river, good 
fresh sections were exposed in the Pliocene. 
Fig. 4.—Section under Magguora. 
GSR SS 
e. Glacial deposit. 
d. Porphyry? 
® | Tertiary. 
3! Shell bed. 
Just after leaving the village the descent commences, and at 
1188 feet by aneroid, the beds are seen resting on the original 
sloping surface of the porphyry (fig. 4), at what must have been 
at one period of their deposition the sea-margin ; for a bed 34 feet 
thick, of a rusty-coloured muddy sand (6'), rests on broken angular 
débris of the adjacent porphyry, buried in a similar sand (a), with 
no admixture of other rocks. 
The base of this bed (6') for a few inches is crowded with marine 
shells, a small Pecten being common; but they are not in a suffi- 
ciently good state of preservation to carry away, or to collect hur- 
riedly, and I had no time to do so in a methodical manner. These 
deposits are horizontal, and extend to the level of the river below, 
1089 feet above sea-level, so that about 100 feet or more of these 
beds are here exposed, blue-grey beds among them (and I noticed 
them low down in the next ravine to the east, the Vallanzana). 
They have all the appearance of having been deposited in a sinking 
area against a steep and originally rocky coast-line. This is an 
