SCIENCE. 
89 
boniferous period. Again it sank, carrying with it 
its store of decayed and decaying vegetation, and an- 
other flood of pebbles rolled over it. 
How many ages were consumed in the process so 
briefly described, who can tell ? Nature’s operations 
are on too vast a scale, and her working time too 
long to admit of hasty activity in the production of 
results. It may well be said that all the years since 
the creation of man would be too short a time to pro- 
duce a bed of coal. 
However long the process just described, it was of 
frequent repetition during the coal period ; and thus 
we find pebble-beds, slate and coal in often recurring 
series, as in the following cross-section made at Tre- 
vorton, the western terminus of the middle Anthracite 
coal basin. 
But through all the changes of time and scene, the 
upheavals and depressions, the submergence and 
emergence of the land, we find a remarkable unifor- 
formity in the growth of plants, continuing almost 
without change throughout ; sigillaria, lepidodendra, 
ferns, etc., following their kind, unvaried through suc- 
cessive series of strata, in each leaving their character- 
istic impress of stems and foliage on the enduring 
tables of the rocks. The coal flora is rich in variety 
and of great beauty, as Professor Lesquereaux’s care- 
ful research abundantly testifies. Their exact forms 
show a quiet condition of the waters, at least during 
the deposit of the slate covering of the coal beds ; and 
the intervening rocks show the same facts. When 
impressions of the flora are found in the solid coal 
itself, we have the same evidence ; but this is of rare 
occurrence. The best impressions usually occur in 
the smooth top slate covering the coal beds. 
When we examine the arrangement of the Pennsyl- 
vania Anthracite beds we wonder at their complexity. 
Without evidence of volcanic disruption, not even a 
protruded trap-dyke, or extensive up or down throw, 
we often find contortions and disturbances of the 
strata. The beds are rarely horizontal, but lie at 
every angle, and sometimes even pass the perpendic- 
ular and fold back upon themselves. In places they 
occupy our mountain summits, nearly 2,000 feet above 
the level of the sea, and again depressed more than 
3,000 feet below it, making a variation of a mile in 
altitude. Yet the coal, which is the frailest material 
in all this rocky mass, is not destroyed, but generally 
in good workable condition — solid, almost crystalized, 
almost pure carbon, and frequently in beds too thick 
for economical working. 
Faults in the Anthracite beds usually have a north- 
west and southeast direction, and show the beds com- 
pressed, and again correspondingly enlarged, but no 
sudden dislocations or breaking off of the strata. 
Soft coal, or dirt faults, are of common occurrence in 
the red ash or softer coals in the western end of the 
Anthracite fields. 
The colored ash of burned coal is due, doubtless, 
to the presence of iron ; but why this coloring matter 
is confined to the upper series of coals in the eastern 
portion of the range, and to the lower beds in the 
western district ; and why there is a gradation in the 
middle district, from white ash in the lower to grey in 
the middle and red in the upper beds, are problems 
yet to be solved. 
How shall we account for the great disturbance of 
the strata from their original horizontal position ? 
Was it caused by volcanic force — of which there are 
no indications — or by contraction of the earth’s crust ? 
And if the latter, why is it confined to the Anthracite 
region, and not extended to the Bituminous also ? 
And how shall we explain the isolation of the smaller 
coal fields, like those of Rhode Island, Richmond, 
Va., or Deep River, in North Carolina; or the dis- 
proportion in quantity between the limited area of 
Anthracite and the widespread fields of Bituminous ? 
Why do we find an abundance of shells and remains 
of animal life in the latter, and rarely any in the 
former ? A few saurian footprints recently found at 
the Ellangowan Colliery, in Schuylkill County, and a 
few shells found in the Glendower Pit, in the Wyoming 
Valley, are signal exceptions to an almost universal 
rule. After an exploration, covering the period from 
1835 to 1850, Prof. H. D. Rogers and his corps of 
assistants failed to find any other specimens. Neither 
has Prof. Lesley in his new Geological Survey of 
Pennsylvania, or the writer in an experience of thirty 
years’ residence and active service, underground and 
in surface explorations, been any more fortunate. 
Nor in all this area do we find a single workable 
bed of iron or limestone, and scarcely a covering of 
fertile soil. The coal once exhausted, nothing is left 
but the worthless shell, desolate and deserted. 
The Anthracite region, mainly confined to one-sixth 
the area of the four mountainous counties of Luzerne, 
Schuylkill, Carbon and Northumberland, in Pennsyl- 
vania, is crowded with an industrious population 
which increased fifty-one per cent in ten years ; that 
is, from 229,700 in i860 to 344,771 in 1870; whilst 
the four adjacent agricultural counties of similar area 
increased in the same time from 319,542 to 339,942, 
only six per cent. It is located on the parallel of 
40° 30', one hundred miles from any seashore, no part 
of it less than 500 feet above tide — near the head- 
waters of the large rivers that drain it — the Susque- 
hanna, Schuylkill, Lehigh and Delaware. The noisy 
trains crossing the valleys and climbing the mountains 
all verge, day and night, to these hives of industry, 
where multitudinous steam engines are hoisting and 
pumping, and breakers crushing. Thousands of miles 
of railroad thread the surface and dive into the inte- 
rior, to roll out the black diamond flood in millions of 
tons of fuel to warm and employ the nation. 
In a second paper, I propose to offer some import- 
ant statistics and information regarding the harvest- 
ing of coal. 
As a supplement to articles in the last November and 
January numbers of the American Journal of Science, John 
M. Stockwell details his investigations into the general 
theory of the moon’s motion as affected by the sun’s attrac- 
tion. While taking a rather despondent view of our pres- 
ent knowledge of the factors in lunar calculation, he admits 
that the general methods of computation are undoubtedly 
correct. 
J. M. Stillman, in August Journal of Science, describes 
the appearance of a new resinous substance in a rocky 
matrix, from San Barnadino, Cal. It is found in detached 
masses, in vein form, over a distance of three miles. He 
seeks to explain its existence by ascribing it to exudations 
from existing conifers, but does not account for its para- 
genesis. 
