New-York tribune., 1841-11-05
Letter Second.

TINS general survey ol lllc tNi'!IpT vi INV
Eternal City must ask you TO follow me be
meath il surface, and with Geology for our guide.
contemplate the works ofthosc mighty agents whose
powers were so long secret even 10 the eye Of
Science. Few spoil, have been the scene Of greater
natural revolution. than the SOIL of Roms. The
,en once flowed in lonely grandeur amidst the wind
inss of her valleys; the SUBMITS OF her highest
hills were washed by the waters of the Iber: and
earthquakes and volcanoes united their rcsstles>
energies 20 the silcpt action of those mder cle-
,nrnts Remote ne the eurlies, epoch of her au-
.hentic history NAV seem bewlldering as the
alaure We have just cast upon these scenes, hal
loved by the most cnnobing recolecuons OF our
race, may appear; time Itself shrnks 10 point IL
the con,emplatiua uf these mysteries of nature. and
you lose sight OF man, il more Immediately IL
the presence of his Maker
Geology teaches us that the plain of Latiun, like
nj, the low-Iands Of the Italian peninsula, was orr
snallv covered with the 1t was while in this
state of sbmcrson that the action ot lis volcanoes
commenced, and by series Of eruptions, oi which
science no longer Prctends 10 hX the date or the
uration gradually raised the first layers Of the fl-
lurc valley above the level OF the waters. The
streams which descended in every direction from
iha adjacent mountains united their currents n
,h-v approached the plain, und the first general
inundation was succeeded by II partial dclugc Of
iresh-wa,cr rivers. IRE gradual accession OF mat
ter thus washed down from the mountains, and the
successive indurdtion of the original murlNe and
volcanic deposits, formed hy degrees more solid
soil which opposing greater resistance TO the i'm
pulse of the rivers. gradually reduced then doHin-
ION, to a narrower compass, and AT length alter
many Il violent outbreak and transient nundation.
confined their currents L. determined channels
Tho casual inequalities of the primitive formation
aud the greater or less resistance thus offered by
different parts Of the passage of the ireSh-wntcl
streams gave rise 10 irregularities in The Surtncc
ai the soil, which became msre defined with each
ncw accession of matter and finally imprinted
upon il that rough and broken exterior which char
ac;e'izeS the immediate precincts OF Romc
These inductions of science, winch might seem
80 SAVIOR somewhat too >,rong yoi theory, are war
ranted by facts that cannot be called in question
Actual examination has every where verified in the
lower parts of Rome the existence OF substratum
which cum only be accounted for by the preceding
Snppo>iiion. Every appearance leads to the belief
tin the basi, of the hills is Of the and
consequently derived from the same cause.
The materials which compose the soil of Rome
are of two classes, distinguished alike in their ma
iure and in their origin Those OF the first class
are derived fran the agency o water those of the
second from fire, or more strictly speaking, from
yolcanoes OF the FIRST there three kinds.
which in various proportions enter into thc com
position OF the soil Of the lower city. The first OF
these is clay combined with certain portion q
calcarcous carbonate, the prese.ce OF which Is de
iectrd by lis instantly cderve>cing upon the ap-
pica;ion of acids Properly speaking TINS Is mail
and from the predominance OF the clayey portion,
should be called clay mar II Is 10 the peculiar
adhesivencsS of this substance tina; the lower city
Is indebted for lis numerous wells. he water
which flows in upon It's layers from the surround
ins hills and finds an easy passage through the
beds of less tenacious earth, an mPenetiab!e
barrier in this, and is thus retaiRed IN pools, OF
ooeying the inclination Of the strata, flows onward
toward the Tiber, with whose current 1t unlies II
rivule;s or drops that filter through the banks
Hence upon the rise of the river its natural outlets
being closed i; collects in larger and inun-
dates the cellars and lower parts q; the city.
In addition To this mari. and sometimes in I'M
mediate mixture with it, i, found calcareou' gra-
/ vel Of = yeowish color. which also in places
contains calcareous pebbles ot considerable mag
ni,ude.
The third clement Of the soil Of the plain is a
sand composed Of petblv grains and more or le>,
intermxed with clay. 1t i of a color nclining to
yellow. spotted with small scales of a sverish mica
and grains OF pirossena. and apparently. though e
| dimensions too subtle TO be clearly distinguished
even with the aid Of the microscope, containius
crystal, of iedspar. The origin of these strata Il.
made evident by the frequent discovery OF fossil
shells and calcareous tuia, both OF kind found
only in layers of tiuyial formation.
Among the volcanic elements OF the .oil OF Rome
!. kind of t,ifa TO which the most distinguished
Of The nstvc geocgis,s has given the name OF f-'a
laoi9e. or the stony This S,aterial was IN sreal
request in the early ages of the city for the con
,,raction Of arches and walls, ana was even occa-
sonaIly used as paving stone for the streets In