Sharp County record., 1885-11-05
THE FORMATION OF COAL.

The Immense Time laken W DrihS @h""o
Present Results-How the Question OF
Time Is Determined.
According to the calculations OF
prominent geologists, the stratum OF
earth that in some places is two miles
and a half thick, constituting the car
boniferous or coal age, was deposited
twenty-nine million years ago. You
will wonder how such calculation can
be made. The result is arrived at by
finding out hoU the different layers are
deposIted, and estimating the larger
ones bv the smaller. As an example.
the same agencies are at work now as
then. Deposits like those of the Dover
Cliffs, England, are being formed at
the bottom of the ocean to-day; anu by
noting the ages of time it takes to RAISE
a given area an inch, by mean seven Oh
the fast-growing coral, we can form
something of a guess how long 1t would
take for two and a half miles OF sohd
covering to form.
During this time, as the name lndl-
Gates, the great beds Of coal IN Penn
sylvania and other sections were
deposited, and as we sit by spark
line coal-fre we are, after all
watching a wood one-the wood OF
twenty-nine million years ago. If you
doubt this, grind piece of coal down
as thin as possible and place 1t under
a microscope, when the woody hDer
will be plainly seen.
Mineral coal is merely the element
of carbon mixed with other bituminous
substances. In the formation of bl-
luminous coal there was loss OF three
fourths of wood and fye-siXths in that
of anthracite. There was a greater
loss bv decomposition, and a reduction
of bulk by pressure from above, and
from this it is assumed that it took
eight feet of leaves and twigS that
dropped from the trees and blew to-
oether. packed closely, to make one
foot of bitumjnous coal, and twelve
feet to make one of anthracite
To make bed OF coal thirty feet
thick, like the one in Wilkesbarre. the
bed of vegetable matter that produced
it must nave been three hundred and
sixty feet thick. Imagine the time it
would take for leaves to drop and
accumulate in solid mass over q great
area as high as the tallest church-spire.
Hence it is that seams or layers OF pure
coal are rarely very thick. Often
times the LAYER is as thin a5 piece OF
paper. but the average is about eight
feet. The Pittsburgh seam. at the place
of the same name, is just this thickness.
and can be seen on the high shores from
the Monongahela River, and traced into
Virginia and Ohio, over an area OF two
hundred and twenty-five by one hun
dred miles. and even into kentucky 1t
varies also in thickness, as in the Cum
berland basin it is fourteen feet thick,
six at Wheeling, five at Athens, o., and
on the Great Kanawha from two to
three feet.
Coal-beds form much quicker under
water where the leaves We're held in
place and retained their gaseous parts
which would be lost in the atmosphere
The common rcat, beds OF to-day are
perhaps coal-beds of the future at
least, they resemble in origin the old
plant-beds. Over one-tenth OF Ireland
is covered with peat-beds, some forty
feet deep. In Massachusetts, alone,
there are over 2O,OOO,O0O cords of it.
Trees are often found buried in them,
and in Ireland a gigantic fossil elk Is
found.
You may wonder where all the car
bon came from that seems to be the
prominent ingredient in coal. 1t IS be-
iieved that in the coal age there was
much more carbon in the atmosphere
than at present, and during this time
it was stored away by the wonderful
plants that were so fitted for the pur-
pose. This, too, purified the air for
the birds and higher forms that came
later
The curious mineral oil, petroleum,
was formed similarly to coal by the de-
composition of vegetable or animal re-
mains. either marine or terrestrial,
buried in mud, in time slowly changing
into oil, or some materials that pro-
ducc it by dstillaton; but oil, unlike
the coal, is found in the layers of all
ares, from the lower Silurian wells Of
kentucky and Tennessee to the Terti'
ary wells of Southern California.
Like other strata, that of the coal
age only appears at the surface at Ger.
tain places-in fact. the total number
of square miles of all the productive
coal-felds in the United States is only
125, 900; in Scotland, 1000 square miles
Ireland, 1,S5O,O00, and in England, q
25O, square miles. Then again, il
is not always represented by coal. II
contains stratifed rocks of all kinds,
sometimes shales, sandstoncs, con
glomeratcs But how, you will ask,
were all these layers placed thereP
Geology shows us that the age just
before the coal was one of submergenct
that is, most of the land was under