OF THE ALPS, NORTH ITALY. 859 
extension to the northward, far down the valley towards the Toce, 
before the great alteration of level which placed this longitudinal 
valley relatively so much above that of Maggiore. That this 
depression of the Lago d’Orta was once an arm of that Tertiary 
sea, I think there is little doubt. We have a southern extension of 
highly fossiliferous Pliocene strata, thirteen miles due south and to 
the west of Borgomanero, as I shall presently describe. These 
marine beds must also have extended east and west across the 
valley, possibly much above this level of about 700 feet above the 
present bottom, taking 500 feet as the maximum depth of the lake*, 
and this long previous to the commencement of the glacial epoch, 
during which they were removed, and that so completely that only 
these remnants now exist. If we examine the position of the rem- 
nant of Buccione, we can easily see how it has been preserved. 
Directly north, and only about 500 yards distant, stands the pro- 
montory of Buccione, a mass of rock rising 250 feet higher, which 
has withstood the whole period of glacial action, and here impeded 
that force southward. These marine beds were thus at an early 
period defended from the direct destructive glacial action, and in 
this sheltered position have been preserved. Directly you pass to 
the west of the Buccione hill and obtain a clear view north down 
the valley, as 1 have shown above, the Tertiary beds disappear. Two 
other similar examples of this accidental preservation of once exten- 
sive deposits, due to their topographical position during the great 
movement of the former gigantic glaciers and their moraine débris 
down the flanks of these mountains towards the plains, came under 
my notice. 
Inst of the Fossils named by Dr. J. Gwyn Jeffreys. 
Arca antiquata, Linné. Nassa costulata, Broccht. Mio- 
Diplodonta rotundata, Montagu. cene and Pliocene. 
Corbula gibba, Olivi. —— turbinellus, Brocchi. 
Natica catena, Da Costa. Bulla utriculus, Brocchi. 
Cassidaria echinophora, LZ. Mio- ovulata, Brocchi. 
cene and Pliocene. Ringicula buccinea, Brocchi. 
He adds :—‘“ In all 10 species. I consider them older Pliocene 
or Plioceno inferiore of the Italian paleontologists.” 
Section AT Boca. 
In the bed of the Strona stream, east of Boca, at 1172 feet above 
sea-level, just above the bridge, four feet of rich ochry sandy clay, 
and thick-bedded red clays, with a bed of conglomerate (having its 
upper surface undulating, as it denuded), are seen in the low bank, 
dipping 35° south-west. The conglomerate is composed of boulders, 
from 2 to 4 inches in diameter, of the adjacent porphyry, with schists 
and granite from the mountains to the north, showing that in early 
Pliocene times their waste was considerable, and that it came from 
the Orta valley. 
* The greatest depth (140 metres, or 459 feet), I am informed by Mr. G. 
Ronchetti of Orta, is between the point of Crabia and the cascade of Acqualba. 
