The Southern herald., 1885-11-21
HOW QUA COAL WAS MADE.

HOW OUR COAL MAS MADE.
The Immense Time Taken to Bring About
Present Resalts-H0w the Question Of
Time l. Determined.
According to the calculations Of
prominent geologists. the stratum Of
earth that in some places is two miles
and half thics, constituting the car
boniferous or coal age, was deposited
twenty-nine million years ago. You
will wonder how such a calculation can
be made The result is arrived at by
indlng ont ho,C the different layers are
deposited. and estimating the larger
ones by the smaller As an example.
.he same agencies are at work now as
hen. Deposits like those Of the Dover
Cliffs, England, are being formed at
the bottom of the ocean to-day; and by
noting the ages of time it takes to raise
given area an inch, by mean seven Of
the fast-growing coral. we can form
something of guess how long it would
take for two and a half miles of solid
covering to form.
During this time. as the name indi-
Gates, the great beds of coal in Penn
;ylvania and other sections were
deposited, and as we sit by a spark
ling 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 it under a
a microscope, when the woody fiber
win be plainly seen.
Mineral coal is merely the element
Of carbon mixed with other bituminous
substances. In the formation of BIZ
luminous coal there was a loss of three
tourths of wood and five-sixths in that
Of anthracite, There was greater
loss by decomposition, and a reduction
Of bulk by pressure from above, and
from this it is assumed that it took
eight feet of leaves and twgs that
dropped from the trees and blew to-
gether, packed closely, to make one
foot Of bitumlnous COAL and twelve
feet to make one Of anthracite.
To make a 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 il
would take for leaves to drop and
accumulate in a solid mass over a 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 as a 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. /
varies also in thickness, as in the Cum
berland basin it is fourteen feet thick
six at Wheeling, five at Athens, o., anC
on the Great Kanawha from two Il
three feet.
Coal-beds form much quicker unde
water, where the leaves were held il
place and retained their gaseous part
which would be lost in the atmosphere
The common peat beds of to-day ar
perhaps coal-beds of the future
least, they resemble in origin the ol,
plant-beds. Over one-tenth of Irelant
is covered with peat-beds, some fort,
feet deep. In Massachusetts, alone
there are over 12O,0OO,0O0 cords of il
Trees are often found buried in them
and in Ireland gigantic fossil elk /
found.
You may wonder where all the car
bon came from that seems to be til
prominent ingredient in coal. II is be
licved that in the coal age there wa
much more carbon in the atmospher
than at present, and during this tim
it was stored away by the wonderful
plants that were so fitted for the pun
pose. This, too, purified the air 70
the birds and higher forms that cam
later.
The curious mineral oil, petroleum
was formed similarly to coal by the dc
composition of vegetable or animal re
mains, either marine or terrestrial
buried in mud, in time slowly changin
into oil, or some materials that pre-
duce it by distillation; but oil, unlik
the coal, is found in the layers of a
ages, from the lower Silurian wells I
Kentucky and Tennessee to the Tert
ary wells of Southern California.
Like other strata, that Of the COS
ige only appears at the surface at Gel
tain places--in fact, the total numbe
Of square miles Of all the productiv
| coal-felds in the United States is onl
$1,000; in Scotland, 1900 square mile
Ireland, 1,S50.00O, and in England, 2
100000 square miles. Then again,
is not always represented by coal.
contains stratified rocks Of all kind
sometimes shales, sandstones, col
glomerates. But how, you will asl
-. al ihnan in,.orn ..lan.d 4l,nrop