Port Tobacco times, and Charles County advertiser. (Port Tobacco, Md.) 1845-1898, 1873-01-17

whose analysis of the molten-nucleus
theory was mainly effective in render
ing that theory untenable, suggested
that there may be isolated subterrane-
an lakes of fiery matter, and that these
may be the true seat of volcanic ener-
gy. But such lakes could not main
tain their heat for ages, if surrounded
Gas the theory requires) by cooler solid
matter, especially as the theory also re-
quires that water should have access
to.them. It will be observed also that
none Of the theories just described af-
fords any direct account of those vari-
Gus features Of the earth's surface
mountain-ranges, table-lands, volcanic
regions, and so on-which are un-
doubtedly due to the action of subter-
ranean forces. The theory advanced
by Mr.. Mallet is open to none Of these
objections. 1t seems, indeed, compe-
tent to explain all the facts which have
hitherto appeared most perplexing.
Itis recognized by physicists that
our earth is gradually parting, with it's
heat. AS it cools it contracts. Now,
if this process of contraction took
place uniformly, no subterranean ac-
tion would result. But, if the interior
contracts more quickly than the crust,
the latter must in. some way Or other
force it's way down to the retreating
nucleus. Mr.. Mallet, shows that the
hotter internal portion must contract
faster than the relatively cool crust !;
and then he shows that the shrinkage
of the crust is competent to occasion
all the known phenomena of volcanic
action. In the distant ages when the
earth was still fashioning, the shrink
age produced the irregularities of level
which we recognize in the elevation of
the land and the depression of the
ocean-bed. Then came the period
when, as the crust shrank, it formed
corrug0tions in other words, when the
foldings and elevations of the some
what thickened. crust gave rise to the
mountain-ranges of the earth; Lastly,
as the globe gradually lost it's extreme
ly high temperature, the continuance
of the same process of shrinkage led no
longer to the formation of ridges and
table-lands, but to local crushing down
and dislocation. This process is still
going on, and Mr.. Malletsn not only re-
cognizes here the origin Of earthquakes,
and of the changes of level now in pro-
gress, but the true cause Of volcanic
heat. The modern theory of heat as a
form of motion here comes into play.
AS the solid crust closes in upon the
shrinking nucleus, the work expended
in crushing down and dislocating the
parts of the crust is transformed into
heat, by which, at the places where
the process goes on with greatest ener-
gy, "the material of the rock so crush
ed and of that adjacent to it are heated
even to fusion. The access of water to
such points determines volcanic erup-
ton"
''Now, all this is not mere theoriz-
ing. Mr.. Mallet does not come before
the scientific world with an ingenious
speculation, which may or may not be
confirmed by observation and expert
ment. He has measured and weighed
the forces of which he speaks. He is
able to tell precisely what proportion
of the actual energy which must be de-
veloped as the earth contracts is neces-
sary for the production of observed
volcanic phenomena. It is probable
that nine-tenths of those who have
read these lines would be disposed to
think that the contraction of the earth
must be far too slow to produce efforts
50 stupendous as those which we re-
oognize in the volcano and the earth
quake. But Mr.. Mallet is able to show,
by calculations which cannot be dis
puted, that less than one-fourth of the
neat at present annually lost by the
earth is sufficient to account for the
5otal annual volcanic action, according
20 the best data at present in our pos
session.
This would clearly not be the place
% follow out Mr.. Mallet's admirable
5heory into all its details. We must
content ourselves with pointing out
low excellently it accounts for certain
oeculiarities of the earth's surface-con-
iguration. Few that have studied
,arefully-drawn charts of the chief
nountain-ranges can have failed to no
ice that the arrangement of these
'anges does not accord with the idea
If upheaval through the action of in
ernal forces. But it will be at once
that the aspect of the noun
accords exactly with what
would be expected to result from such |
! process of contraction as Mr.. Mallet
las indicated. The shrivelled skin of
IN apple affords no oinaptrepresentation
If the corrugated surface of our earth,
md, according to the new theory, the
hrivelling of such skin is precisely |
analogous to the processes at work
lpon the earth when mountain-ranges
we're being formed. Again, there are
ew students of geology who have not
ound source of perplexity in the
oldings and overlappings of strata in
mountainous regions. No forces of
lpheavel seem competent to produce
his arrangement. But by the new
heorv this feature of the oarth's sur