Frostburg mining journal. [volume] (Frostburg, Md.) 1871-1913, 1873-03-08

COal--Its Origin.
A mistaken impression is somewhat
widely prevalent that, in the coal
fields, We have the remains of ancient
forests-in other words, it is supposed
that wherever there was forest in
primeval times there now exists coal
field Of greater or less extent. In con-
nection with this view, also the opin-
ion is entertained that the forests now
in existence will in the process of
time and after due geological changes,
become the coal beds Of the future
ages. But although as we shall pre-
sently see, the coal fields are undoubt-
edly due to the vegetation of former
eras it is far from being the case that
the primeval forests became converted
in general way into coal. Condi-
tons Of a peculiar and to some extent
exceptional character were requisite
for the foundation of coal-felds If
we consider the evidence given by the
coal fields, we shall see what these
conditions were The beds or seams
of coal form but small portion of the
thickness of the great geological group
of strata to which they for the most
part appertain This group is called
the carboniferous, and not uncommon.
ly 1.-The Coal = but evea where GOAL is
most abundant, it forms only minute
part of the whole mass. Thus it has
been estimated, Sir Charles Lyell tells
US, that ia South Wales the thickness
Of the carboniferous strata amounts,
in all, to between 1000 and 10000
feet Tor more than two miles y but
the various coal seams do not, )" accord,
ing to Professor Phillips, exceed in
the aggregate 100 feet" or less than
one hundredth part of The whole. In
North Lancashire the carboniferous
strata occupy depth Of more than
three miles Here no fewer than eigh-
tv seams of coal have been counted
(seventy- one having been exposed by
the action of the sea !; } but these seams
are nowhere more than FIVE feet in
thickness and many are but few In
ches thick Thus it is evident that
the formation Of coal can have been in
progress but short portion of the time
during which the corbonlferous series
of strata was in process of deposition.
Throughout by far the greater portion
of that time other minerals are being
deposited. 1t is next to be noticed
that under each coal seam a stratum
of ancient soil exists, in which there
are commonly found the roots of an
cient trees, while above the coal there
is commonly layer of shale or sand
stone, in which not unfrequently the
trunks of those trees are found either
fallen orstill in their original position,
and only partly converted into coal -
The bark remains. but is transmitted
into coal; the hollow of the trunk,
decaving long before the trunk gave
way, is represented by cast in sand
stone. Thus, if we try to picture to
ourselves the state of things which eX-
listed when such seam Of coal first
began to be covered up by the higher
deposit, we see that there must have
been trees standing erect above lay
er of vegetable matter, the roots of the
trees being imbedded in the soil which
forms the der osit next below the coal.
The vegetable layers may probably
have been two or three times as thick
as the resulting coal seam, and were
reduced by pressure to their present
thickness but such layers can not at
anytime have reached the branches Of
the forest trees. Then the process Of
deposition began. This can only have
happened when some subsidence of the
soil had caused it to be submerged to
a greater or less depth. We can infer
from the depth of the strata everything
the coal seams that this state of sub
mergence continued in many cases for
a long period of time, and it is equal
w clear that the formation of the veg
etable layers themselves has been a
process occupying q considerable time,
since tail tress grew before the next
submergence took place So soon as
submergence was complete the tall
trees persisted and began to decay
The stout trunks above the vegetable
layer were broken off and swept away
BY the sea. The forest itself, proha
bly, so called, was for the most part
destroyed. twas the decaying refuse
of the forest, intermixed with the low
err growths, which formed the coal
seams as it now exists Among these
were the lower parts of the trunks Of
the ancient forest trees. These be-
came converted, like the rest Of vege-
table matter, into eoal-Cornh,N
Magazine,
PROTECTION OF MINERs.-In late
i N Z l.