The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1842-03-21

mountain 10 opposed; and, therefore, when in the
| apse OF lime the face Of one volcanic mountain
becomes worn away by the action Of frost, and rain
and exposure to the action of the atmosphere, the
basal dyke by being much harder, resists all such
action, and projects from the rest Of the mountain
as we see IN this diagram (Here he pointed to .
diagram representing basalt dyke traversing .
volcanic mountain in the interior Of the island Of
| Madeira, and the same dyke traversing another
| mountain on the sea coast, and dipping into the
Atlantic ocean, In l669, during the great erup'
the nature Of the formation of these dykes. Etns
was then rent open, and through this assure was
| seen the incandescent lava foaming and boiling up,
with the evidence also that it existed to some
the large rents and cracks in the mountains, and
iormed dykes. question has been asked why
the Older parts OF Etna net overrun and cover
60 up by the newer eiuptions! The answer to
prevented such result; and also the general din
thereby given to the beds. For, ON going refund
the mountain, find that the beds din in all d.
rections; those on the east side dip to the east
those ON the north side dip to the north; those on
the south side to the south; and the west TO the
west. And this has probably tended much to pre-
vent the old parts of the mountain from being
covered up BY this lava more recently thrown oat:
And, again, the general upheaval Of the whole Of
this enormous mountain from below, which we
know has taken place. Etna rests ON shell for
nation OF a recent origin. And the force which
we see has carried up the marine formation that
also carried up the whole mountaiR. The mass of
the newer eruPtive matter is Of supra-marine ORR
SIN. So that we come to the conclusion that some
40O0 feet Of Etna was formed in the open air as
Mount Dor was formed. II was originally
mountain some 5000 feet high, and then BY the up
heaval forces below nine tenths Of which is steam,
at q high tsmPsrature and under enormous pres
ure, it elevated to its present lofty position
And then another reason why the older parts have
net been covered by the more recent eruptions
may Do, that Ter every one eruption on the summit
there have been two on the margin, or side, of
the mountain For it is an invariabe rule that the
higher the mass is heaved up the greater is the by.
drostatic pressure, and therefore eruptions must
oreak out more frequently on the TANKS than the
TOP: OF high Mountains We have better history
OF Mount Etna than Of any other volcano ON the
earth. We have very good accounts by Diodorus
scslus Of an eruption of E:na before the Trojan
War, which compelled the inhabitants of that dis
trict to leave the island. Thucydidss mentions
three eruPtions which took place before the pelo-
ponession war The second Of these eruptions
spoken Of by Thucydides is the one which is 60
beautifully described in the I'd Pythian Ode Of
Pindsr. And his description proves to US that the
same scenes and events took place at an eruption
OF Etna, then AS b c., which occurred in Ammo
Domini, 1863, when the town Of Catana was de-
stroyed. He speaks of it as-"the snowy EtAa-
the pillar Of nurse Of everlasting frost
"a stream of salient smoke by day, and vivid fame
by night, &c." And it is a remarkable fact, that
in soae way not properly accounted for by chem
ists steam is entangled and mixed with all the lava
VI tuese Voicanoss hlS was seen AZ the eruption
in 1919, when the lava was moving through the Val
Demone to the sea. My friend, Mr. Scrope, saw
tins when 1t was moving at the rate Of about yard
an honr; and steam was issuing from it in large
its own making, of scOria, the outside of which is
very hard. And it moves directly onwards, in
consequences Of this crust, up rising ground, never
deviatlng to the right or left. And when Catania
was threatened by this lava, the Count P collect.
ed bedy men armed with pickaxes who turned out
and attacked the sides sf this lava, and cut hole
Ia it and tapped it, aud stream Of lava fowed out
towards the village Of Palazzolo; but the inhsbi-
SEES also turned ont. and prevented the stream of
lava from being brought in that direction. The la
va Kept still going on towards Catania, the people
all turned out as they would against common enc.
my, and built a rampant Of hewn stone sixty feet
high to arrest the progress OF the lava But on il
came; and when it reached the rampant instead of
turning of, kept ON accommodating in spot, and
rising higher and higher, until it topped the ram.
part, and then forming curve over the summit of
the barrier it cascaded into the city, destroying
half the place, and went straight on to the sea- into
which it sushed Kissing and cracking, sthe r cks
with loud uProar",ss described by Pindar. After
Catana, he had this mass dug into where it crossed
the wall, and it is to be at this day having all
the appearance Of pctri6ed cascade. Great sem
Etna has been formed probably by the sinking down
of the earth; nor is this difficult to believe, since
we find that IN Java at the beginning Of the 18th
century, mountain there lost 1000 feet OF its height
by the settling down OF the earth. (Here Mr.. Lyell
pointed to the two cones of Etna, which were
thrown up 1911 aud 1Sl9 and the two older cones
close by, that are spoken of by Pliny and the An.
cients.) The materials Of which the whole of Ell
na is com posed are singularly homogeneous. The
recent cones are composed Of augite (Which is
something like hornblade) and Kind Of felspar
called Labradorite; a large quantity Of iron, and
some titania. These materials are analogous to
those in Of the oldest rocks in the series; and
SO also Of the materials forming the older Of
Etna. In the base of the older cones we find
mass Of matter Of granite structure several hun.
dred feet high; il is like granite, and Just as
we should have expected that material to have
looked cooling slowly, and under great pressure
These granite rocks which not stratifed and
are not volcanic are termed plutonic. The volcanic
Of great depth less porous and more crystalline
than those on the surface; and so it is with the
mass of grantic matter found at the base of Etna;
it is less porous aud more chrystalline than more
Plutonic rocks consist OF series porphyry rocks,
but not scoria, or volcanic sand pebbles, or any
thing indicating that they were forced on the sur
face. And as the name Volcano was given to
Etna because 1t was supposed that there Vulcan
had his forge, so the name Plutonic was given
to the rocks formed at great depth, because
Pluto was the presiding deity of the region of the
internal fires Of the EARTH where Phlesethon, the
ed. [Some smiling by the ladies ] And Lethe-
an influence is exerted by these deep beds Of lava
for by act they destroy all traces of organic re.
mains in other rocks. Mae ten:hs Of all the mat
ter in volcanic eruptiens is steam at an no.mous
heat, and under tremendous pressure. And as the
lava and steam comes into contact with other rocks
the latter enters their pores cry stalzes them, and
destroys all trace Of organic remains. We see
this in the Lipari Islands, we see 1t near Corinth
and in various parts Of Greece. So also we see il
in the Carrara marble, which is crystalIzed and
freed from organic traces by similar process The
manner in which this has been produced, as well as
many points in the history Of these rocks, must
mann an ny pot hesis for some time We cannot tell
what length Of time it took to form Mount Etna,
There over eighty cones this mountain; and
not more than twenty have been formed since the
most ancient period to which Diodorus Siculus re-
the ladies looked as.onished at each ether And
suppose these eighty cones were all formed in
twelve thousand years II we strip all Of them from
the mountain-wonserfulm marks and monuments A.
they are Of The earth's history for the last twelve