Daily globe. [volume] (St. Paul, Minn.) 1878-1884, 1883-03-06

WabashaW street. Prof. Daniels gave a
lecture upon the geology of the coal for
nation which contained many facts of in
terest and was illustrated by specimens
and views. He spoke substantially as fol-
lows:
Mineral coal, or stone coal as it is some
times called, is gene rally found associated
with a series of rocks known as the coal
formation. These rocks differ materially
in different localities in accidental quail
ties. They are usually limestone, sand
stone, conglomerates, and always con-
siderable bodies of shale, slate, and hard
ened clay. The coal occurs as an included
bed. The rocks are always in distinct
layers or strata, and the coal beds are in
cluded among them usually as a parallel
layer. 1t is not proper to speak of a coal
seam as vein, but it should be called q
seam, bed or deposit.
Whatever may be the chemical constitu
ents, or the character of the rocks, which
attend the coal, they always show clear
evidence of being deposits in clear water.
They frequently abound in marine
fossils such as shells, corals and tril-
lobites, and remains of fishes are also
found, often very perfectly preserved. But
the Astounding forms of these rocks are
those of plants. These fossils constitute
the characteristic of the coal formation,
but they are all land plants, belonging to
species now extinct. They are preserved
with wonderful perfection in the fine
grained states. In these rocks delicate
ferns are preserved as perfectly as in the
herbarium of the most skilltul botanist
Every minute detail of venation upon the
leaves, and even the delicate seed spores,
have been handed down to Us as perfect as
in life. In the halls and galleries of ex
tensiye coal mines, these plants are seen
grouped together in wonderful variety and
furnishing frescoes upon the rocky ceiling
overhead, rivaling the most per-
feet work of art. By the study
of these forms we are enabled to restore
the conditions of the period when they
grew. They point US directly to the orr
gin of the coal, and indeed they constitute
the most important part Of the machinery
by which the vast stores of fossil fuel have
been formed. The fossil plants of the
coal formation have been studied by our
most eminent botanists. They include
thousands Of species, some of vast size,
belonging to fora similar to that now
growing only in the tropics. The abun-
dance OF these forms proves beyond cues
ton that they grew nearly where they are
found. tropical climate is therefore in
ferred for those regions where coal seams
and their attendant fossils are now found.
It is also proved that the surface where
the plants grew was generally low, and
even marshy. A moist condition of the
atmosphere generally obtained, and an
amount of carbonic acid much greater
than exists in the air. These conditions
were all favorable to vegetable growth.
The land existed mostly as islands slowly
elevated above the sea. On these low-lying
lands, nursed into gigantic growth by
heat, moisture and the very impurities of
the air, a gigantic vegetation spread
everywhere over the land. Hugh Miller
speaks of this as an Era of Vegetation,
and says that to other planets our earth
must have shown with a delicate green
ray.
We have here some we'll preserved speci-
mems of the strange, gigantic forms of
that period. Here is piece of the scaly
bark of large trunk called the Sepido-
dendron. which is often mistaken by
miners for the scaly skin of fish or rep
tile. This plant grew to
the height of eighty or
100 feet, and waved its tall head in the
breezes of the coal period many, many
years ago. Here is the highly ornate bark
of the Sidularia, and here specimens of a
gigantic reed from the great sandstones of
the Cumberland mountains. Here are
ferns in as delicate tracery upon those
light colored shales as any picture done
in crayon by the most skillful hand. There
are pictures from the leaves of the great
Stone Book, done by the hands of an un-
erring artist, and illustrating the great
epic of the geological ages.
The coal period was one of great vol
canic disturbance, constant changes of
level occurred. Large areas of land slow
ly elevated above the water became the
sites of this dense vegetation,
and then subsidized beneath the
level of the sea, bearing
down with them the wealth of plant life
which they sustained. The sediments of
the ocean slowly accumulated above them,
burying huge conifers and delicate moses
alike upon the ocean floor. The chemical
forces acting upon the buried mass slowly
changed its substance into coal. The
pressure Of the waters and beds of clay,
sand and lime stone condensed it into the
smallest possible space. Thus was formed
that vast store of fossil fuel to which mod
ern civilization owes so great debt.
The bottom of the sea was again elevated
and became surface; again the vegetation
spread over it with its wonted luxuriance
and again it sunk. In some To-
calities we have indubitable evidence that
this succession took place not less than
twenty times. In some cases these dis
turbances werc attended with fractures in
the crust and the out-throw of lavas. The
coal around such centers of disturbance
has been greatly changed in its original
character. In its original form all Goa
belongs to the soft or bituminous variety
such as we find in Illinois and Iowa. BY
the action of volcanic emanations in high
~ disturbed portions of the coal field this
coal is found changed into anthracite Of
hard coal. Anthracite coal may be con
sidered a natural charcoal. The volcanic
heat separated the volatile portions of The
coal and left the carbon by a pro
T.