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which leads to Mo n t Cenis, nms through its who l e extent. Tl i c third valley proceeds iti
a fouthcni diretftion f rom Tu r i n , and leads to the eity of Coi i i and the Col de Tende , the
fceond g r and pa f f agc . It is conf iderably longe r and wider than the others, and is watered
in great mealure by the P ô and the Ma i r a , which f lows at the foot of Mo n t Argentera, and
uni tes wi th the Pô near Mi r a bnina .
Th e f e three g r and valleys, as well as other s of the f ame kind, but lefs extenfive, feem
vifibly to ihew the road traced b y the water s of the fea, when, wi th an accelerated mot ion,
they precipi tated themfelves from the hi gh elevated fummi t s of the Alps into this delightful
plain, hur l ing and rol l ing before them vai l ma f f e s of i lone s and earth, which they had det
ached f rom the pe aks o f the pr imordi a l chain, and of wiiich the gi-eateil part of the Pi edmontefe
and Mont f e r r a t hills feem to be formed.
I t is doubt lef s the teiTible e f f e a s o f that great and t remendous revolut ion whi ch has
fo totally chang ed the fur f ace of our continents, and which Monf . de S auf fur e fo jni l ly
calls gr and débâcle ; an event whi ch, though its efFeits and a f t i ons have been terrific, yet
is certainly not of f o remote a date as many phi lofopher s fuppof e , who calculate this
c po cha at fome thouf ands of centuries. I am therefore of opinion, that this gr and débâcle
ha s foi-med, or rather traced out , our l a rge pr imordi a l valleys, and that the dimini ihed
a é l ions of the fea ha s br ought them to a flate of perfedt ion nearly as they now appear , as
well by the e f fbi t of its current, as b y that of its fediment s. It is l ikewi fe to this f é cond
a f t i o n that we mu f t attribute the format ion of the fecondary mount a ins , whi ch border the
who l e count ry of L omb a r d y , and whi ch are filled wi th ma r ine folfils, and a mi x tur e of
primi t ive and fecondary ftones, often found in a confufed ftate in thofe heterogeneous
mount a ins , the who l e forming together a kind of ama l gum, whi ch feems unque i l ionably
to prove that there have been two epoehas whi ch have near ly fol lowed each other.
T h e repeated aiiiion of the torrents has, in procef s of time, br ought this work to
pe r f e f t i on, and even ftill continues b y the accumulat ions to increafe (as we have already
obfei-ved) the bounda r i e s of this beaut i ful count ry, and give it (hat regular and imi form
declivity whi ch adds fo conf iderably to the fertility and falubrity of Pi edmont .
Th e f e ref lect ions , which to fome ma y probably appe a r vifionary, or merely theoretic,
feem to me to b e the mo f t natural and fatisfaibory manne r of account ing for the var ious
phenomena which I have had occaf ion to obferve, not only in Italy, but in the different
part s of E u r o p e that I have vifited.
Wh a t I have here advanced concerning the format ion of the valley of Lombnrdy, I
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confidcr as equal ly appl icable where f imi lar ef fect s are obfer\'able. T h o f c ideas have al fo
greatly aflifted me in a c count ing for tlie very fingular format ion of mo l l of the hills of
Piedmont , and particularly thofe which are fituated foutli of the city of T u r i n ; a cliain
whi ch extends nine mi les in length, and four in widdi , viz. "Mo n t a g n e s des Capuc ins ,
Sup e r gua , " &c. entirely formed of matter foreign to the places where they i l and, and
covered, in many pai-ts, by h u g e blocks of granite, which are fcattered here and there,
befides a variety of primi t ive ftones, f ome round, others irregulai-, but mo f t of them incruftated
with a kind of yellow and grey mar ie, or ma rg a , filled wi th mai'itime and fluviatile
fticlls • ; others pl a c ed among l l a fpecies of calcareous ftrata, filled only wi th ma r ine
folfils. The f e obfervations, l ikewi fe, led me to account for the me ans b y whi ch thofe
enormous mafies of granite, of at leaft thirty-nine feet in circumference, have found tlieir
wa y to thofe elevations, whi ch arc upwa rds of feven hundr ed feet above the plain. F o r as
no conceivable force feems c apable of ra i f ing fuch cnoi-mous niafles to fo vaft a height ,
except , perhaps , by the me ans of water or fire ( f u p p o fmg that fome volcanic a f t i o n be
propor t ional to fuch e f f e f t ) ; but as there ha s not yet appe a r ed any volcanic remains in this
ne ighbourhood, it amount s a lmof t to a certainty, that they have been rai fcd b y the accelei
ated a i t i o n of the waters only, wluch have driven them to the height where they now are
found. No t , indeed, b y reverfing b y its own adl ion tlie l aws of gravi tat ion, but folely
owing to the reiterated effedl of the fecondary retreat of tliis element, whi ch, by the atflion
of its current, added to tliofe of the torrents whi ch defcend f rom thofe elevated pe aks ,
ha d entirely waf i ied away the foil wliich luiited thefe mount a ins to the gr and pr imordi a l
chaiii, tliat is, pr ior to their being ifolated as (hey now are. Mu c h mor e mi ght be added
to prove what I have advanced, but as I fliaU have occaf ion to touch u p o n this f u b j eA
a g a in in the cour fe of this wo rk, I ihall defift for the prefcnt , and proc e ed to Coni , and
f rom thence to L imon, in order to paf s tlie Col dc Tende , one of the tlirce g r and i
to Italy acrofs the Alps .
* Shells generally found in rivers,