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 1 &5°i 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. 



