The Manitowoc pilot. [volume] (Manitowoc, Wis.) 1859-1932, 1886-05-06
THE EARTH'S PAST.

recognized as presenting stupendously
difficult series of problems-problem:
indeed which can never be fully solved
So soon as ,oen gave up the old ides
that the crust had been fashioned origi
nalIy much as it is now; so soon as
turning over the leaves OF the grea
earth volume, they began tc read wha
is recorded there, they found IN tht
first place, that the record runs bach
over millions of past years, and, in tn
second place, that it is full of gaps, ..
blurred pages, of scarce interpretable
passages. Yet imperfect though the
record is in many places, and hard to
read i'll others, it at least tells us clearly
the general history of the earth from the
time when first there were lands and
seas on her surface as now, and when
the rival forces of denudation on the
one hand and of land making on the
other began the contest which has con.
tinued for millions of years in the past,
and will last for millions of years yet to
come.
We no longer. indeed, look back over
such uniform series of changes as the
earlier students of geology contemplate
ed We no longer regard the layers OF
the earth as comparable with those OF
an onion, or formed in uniform success
sion as to time. We see, for example,
that even as, in our own age, the denud-
ing forces are forming new strata out OF
the materials of Quaternary rocks here,
out of Tertiary rocks there, of Cretace-
Gus, Jurassic, and Triassic rocks else
where, and in other vast regions, even
out of the primary rocks down to the
Lower Silurian and Cambrian, nav
even to the Archaan rocks themselves, SO
it has been all the time. The crust OF
the earth has never presented features
purely Pleistocene, or Piliocene, or Mio-
cene-or presented, indeed, any uni
form aspect at ALL and as the forma-
tions have never been uniformly pre-
sented, SO also the strata has never been
uniformly laid down. We can no more
say the earth was at one time Carboni-
ferrous and at another Cretaceous, than
we can say that the soil of England
was in such and such an era waste, at
another time pasture land, at another
crop land.
Yet we can look back over the past
history of the earth and recognize her
constant, though not uniform progress
sion from her Archaan condition to her
present state.
The problems thus presented by the
earth's history, while stupendously diff
cult in detail, are yet so far soluble that
we can find in the action of air and
water on the one hand, and subterra-
mean forces on the other, the explanation
OF the general progression of the earth to
her present condition. 1t is otherwise
with those prior changes by which the
earth passed to the stage when she was
fit to be the abode of living creatures.
We have evidence, indeed, here also,
but 1t is not so close at hand. We have
knowledge of the chemical and physi-
cal laws involved in the problem, but
the conditions under which the processes
then taking place proceeded were un-
like any under which we can now ex-
pertinent. So far as | know, the prob
lens suggested by the consideration of
the earth's fiery youth have not been as
II very closely dealt with. Let us note
some of the evidence, and some of the
points which may fairly be regarded as
clear.
In the first place, think we are too
apt to regard planet in its fiery youth
as more uniform than the earth is as we
recognize it now. We find the idea
common that there would be a molten
mass, with perhaps a solid nucleus and
a solid crust, and outside that complex
atmospheric envelope, high up, in which
would be suspended immense layers of
cloud, enshrouding the real planet from
outside view. These ideas seem as like
ly to be erroneous pc the common idea
of the earth as inclosed in uniform
series of strata before wind. rain, and
storm cut her surface up into mountains
and valleys, hills and dales, ravines and
gorges. Probably the structure of the
earth, when in its fiery youth, was even
very much more complex than the con-
tour OF the earth's crust is now. All the
conditions favored tremendous distur-
Dances. The upheavals and down.
sinkings of the crust, for instance,
would be very much more active then
than now, though it does not follow that
the resulting inequalities of level would
be greater. Indeed, they would not be
nearly so great, for the simple reason
that, whatever the actual materials of
the forming crust in those times, the in
tense heat pervading it would suffice to
render it too unstable 20 be able to
stand out to very great heights above
the mean level. But consider how rap
idly it would be changed by the sub
aerial forces which in those days must
have been at work.
On our present earth we have sn at
mosphere of oxygen and nitrogen pro-
ducing pressure of about Is pounds to
the square inch; water is from time to
time added to it in the form of vapor
raised by the suns heat from the sea,
and it is this water, forming into clouds,
and pouring down on the land, which
leads to all the denuding work Of river,
cataract, rain, snow, ice, and glacier.
In addition there is the direct denuding
action of the air in wind and storm, the
direct denuding action of watct as the
waves of the sea pulsate on tleir shore
lines.
But such denuding forces can be alb
solutely as nothing compared with the
denuding forces which must have been
in operation when the earth was Young
1t is certain that the oxygen and nitro
gen now present IN the air are but a
reSiduum of what was once there But
besides these gases, now in due proper
ton for the support of the eartR's life,
there were immense quantities of car
bonic acid gas, of sulphurous acid, sui
phureted hydrogen, chlorine, boracic
acid, and other destructive gases, some
ready to assume the liquid form, and so
to he still more destructive Put there
would also be immense quantities
whole oceans one may say-of water in
the form of vapor. The pressure of that
primeval atmosphere would have been
so great that the waters of such oceans
as would have existed then would not
have turned into steam, save at tenn
perature so far above the boiling point
at the present atmospheric pressure
that the surface of the ocean would
actually have glowed with inherent
Iuster: The water vapor in the air
would have been no such cool and
n N