NATURAL. 
the P6; from the extreme variation 
or great variety existing in the dif. 
ferent strata of sand, pebbles, and 
vegetable earth, which now form 
the banks of that wonderful river ; 
from the number of beds of mari- 
time and fluviatiles, or river shells, 
which lieinsome places distinct or 
separated, and in others confusedly 
mixed together, from Cremona to 
the sea: in fine, from the progres- 
sive diminution which the velocity 
of the waters of the P6 experience, 
in proportion as the lower valley of 
Lombardy enlarges and gets nearer 
the sea; I conclude or deduce the 
following consequences. 1. That 
that part of the valley, which lies 
eastward of Cremona, cannot owe 
its origin or increase but to the 
quantities of earthy matter continu- 
ally brought down and deposited by 
this river, which, to all appear- 
ances, were formerly infinitely more 
considerable than at present. 2. 
That the sea once covered this fer- 
tile plain; and that the greatest 
part of Lombardy may be consider- 
ed as an encroachment made on 
that element, by a quantity of frag- 
ments detached from the primordial 
and secondary chain of mountains, 
which were at first hurled by the sea 
in its last retreat, and then carried 
along by the waters of the Pd, which 
in some degree still continues to de- 
posit them, as before mentioned, by 
meansof the frequent imundations 
caused by the overflowings of the 
P6 in the confines of Ferrara and 
Bologna, which are. increased by 
the eagerness of the inhabitants of 
those provinces, who unfortunately 
attempted to restrain the waters of 
that formidable river too soon by 
banks, dykes, &c. ¥ 
If. From the direction of the val- 
ley of Lombardy, and of all the se= 
HISTORY. {*7k 
condary ones which terminate ia it ; 
from the extreme difference in the 
elevation of the head of these se- 
condary valleys situated at the foot 
of the Alps, and likewise from their 
number, compared to those on the 
west and south-west of .the same 
mountains; from their irregular 
form, number, and great degree of 
abruptness, which exist likewise in 
the secondary and tertiary moun- 
tains on the eastern side of the grani- 
tic peaks, in comparison to those of 
the same order on the western: in 
short, from the calcareous chain of 
hills which surround all Lombardy : 
I think I may venture to conclude : 
1. That the motion of the sea, in 
its first mutation or change, hada 
direction tending nearly from west — 
toeast. 2. That at first it rose toa 
great height, which appears to be 
fully proved by the calcareous mat- 
ter, containing maritime shells, now 
found lying on some of the primi- 
tive rocks of the Alps. 3. That 
its motion and retreat, or subsiding, 
were at first extremely rapid. 4, 
That the seas having rose above the 
plains which form the high valleys 
of the Alps, it afterwards precipi- 
tated itself towards the east, and 
dug by its weight and velocity the 
valleys which are at their feet, mu- 
tilating and chamfretting the secon- 
dary mountains which intercepted 
its passage. 5. That the sea, having 
in process of time abated in its mo- 
tion, had by its sediment formed 
the schistus and secondary moun- 
tains, which describe a kind of zone 
to the plain of Lombardy : in short, 
6. That it is evident, that the sea 
remained or stopped a much longer 
time on the western side than of the 
eastern, 
III. From the enormous masses 
of granite and primitive rock whicl 
[*E 4] how 
