It is an error to suppose that the petroleum and inflammable gases of the great rock-oil region above sketched are all restricted to the coal

petroleums, and the carbureted hydrogen gases. | of the causes which control their local distribuBitumen properly embraces several hydrocar- tion, let us examine the rock-oils and gases in bons, some solid, some liquid. Asphaltum, one their general geological relationships. of them, is a brownish-black solid substance, of bright fracture, and burning with a brilliant flame; and naphtha, another chief ingredient, is, when pure, a colorless liquid of bituminous measures, or even to the carboniferous formaodor, and a specific gravity about three-fourths that of water. Petroleum, strictly defined, is a dark-colored liquid compound of the hydrocarbons, containing much naphtha. Asphaltum in a semi-solid shape abounds on the shores of the Dead Sea; it also borders the famous bitumen lake of the Island of Trinidad. Naphtha flows profusely from the ground in some localities in Persia, also in the Birman Empire. It is stated that at Rangoon there are upward of 500 wells of naphtha, yielding annually more than 400,000 hogsheads of the oil. The bitumen lake in Trinidad is half a mile in breadth; the materials are solid at its shores, but liquid and even boiling toward its centre. This lake is said to repose upon a bed of coal.

tion. Geologists of the United States and of the adjoining British Provinces have clearly shown that they rise from strata in those regions seated far beneath the coal. The stratified rocks of the region consist of an immense development of Silurian, Devonian, and Carboniferous deposits of an aggregate depth or thickness of not less than 25,000 or 30,000 feet, or some five or six miles. They include, at the least, three or four continuous and widely-diffused great beds, of a magnitude entitling them to be called formations, whose chemical nature well adapts them to yielding mineral oils and carbureted gases as copiously as do any coal measures. The lowest placed or oldest of these, the Utica black shale, ranging in its outcrop from east to west through New Of petroleum by far the most abounding dis- York, and thence northwest through Canada, trict known is that in North America, now at- has a variable thickness amounting in some tracting so much attention. This wide region places to 300 feet; this rock is, for the most of the rock-oils extends from the southern por- part, a crumbly shale, of a prevailingly darktion of the Ohio Valley to Georgian Bay of Lake bluish or brownish-black color, and it abounds Huron in Upper Canada, and from the Allegha- in bituminous and carbonaceous products; it nies in Pennsylvania to the western limits of the even contains a few thin coaly layers, and has bituminous coal-fields in the vicinity of the Mis- often been mistaken for a genuine coal-bearing souri River. The material has been found in formation. So charged is it with mineral charVirginia, Maryland, Pennsylvania, New York, coal that it has been in certain localities conOhio, Michigan, Kentucky, Tennessee, Kansas, verted into a black pigment. It is replete in Illinois, Texas, and California. Of course this many places in fossil sea-weeds and fucoids, and general statement does not imply that the petro- there can be little doubt that it owes its richness leum is to be met with every where throughout in carbonaceous matter mainly to these plants. the wide area thus vaguely defined. On the Petroleum is known, indeed, to issue plentifulcontrary, we know that hitherto it has been ly from this rock on the Great Manitoulin Islfound only in scattered localities within these and in Lake Huron. It underlies, let it be oblimits. Of the more specially productive oil-served, all the higher Silurian, Devonian, and fields the best known and hitherto most abound- Carboniferous strata which in succession occupy ing one is a broad area embracing a part of Canada West from Lake Ontario to Lake Huron, and portions of Western New York and Western Pennsylvania, the southeastern half of Ohio, all Northwestern Virginia, and the eastern districts of Kentucky. The approximate centre of this wide region so profusely "running with oil," is somewhere near Marietta, on the Ohio River, and the superficial extent of it can not be less than about 50,000 square miles.

long east and west-trending zones of country to the south of its outcrop in New York, Pennsylvania, Michigan, and Ohio. To it chiefly must we credit the petroleum and gas-springs, which occur north or outside of the districts occupied by the gently south-dipping Devonian and Carboniferous strata.

Ascending in the series of the old or Paleozoic formations, we come in stratigraphical order, at an interval of many, say from ten to fifteen thouGeologists familiar with the great petroleum sand feet, to other yet thicker or more massive tract entertain no doubt that the rocky strata deposits of very similarly constituted dark carwithin its limits are, in almost every square mile bonaceous and bituminous shale and slate rocks of it, more or less impregnated with the precious of the Devonian period, and known in the geofluid and its gaseous adjuncts, but not every logical survey of New York as the Marcellus where in the same high degree. Indeed, a shale and the Genesee shale, and in that of merely superficial exploration of the country will Pennsylvania as the cadent lower and upper convince that the subterranean oils and gases black slates. In the latter-named State these are distributed very unequally through the vast formations attain a maximum thickness respectterritory. I shall essay to show before this ively of 800 and 700 feet; but in New York and brief description closes by what law these prod-in the Northwestern States they are much thinucts seem to arrange themselves in more or less ner, the Marcellus rarely exceeding fifty feet, regular zones of comparative abundance and and the Genesee shale seldom measuring more scarcity. But preliminary to this exposition than twenty-five feet, which is its average bulk

the coaly or carbonaceous beds in the regions further west. There the subterranean action did not wholly dispel the hydrocarbons, but merely saturated or infiltered the pores, crevices, and fissures of the overresting rocks more or less fully with them. The anthracite belt is like a row of loaves or puddings in a cook's unequallyheated oven, where an excess of warmth has

at its outcrop near Lake Erie. Further Southwest it is thicker. They are both of them very bituminous strata, and they encompass and pass under all the great Western coal-fields, at depths below the coal-beds of only a few thousand feet. Thus they can as readily have contributed, we may conceive, as the coal itself to the bituminizing or impregnating with the hydrocarbons all those portions of the upper strata where the cir-dried the dishes to a crust, whereas the other cumstances have been conducive to the discharge of the volatile products, and their retention in the pores and crevices of the rocks nearer the surface.

There are still other members or subdivisions of the great Paleozoic system of strata underneath the coal measures, that upon examination will show a sufficiency of bituminous constituents to convince us that they too may have assisted in charging the overlying coal containing sandstones and shales with mineral oils and gases.

more and more bituminous belts are in the state of articles less and less baked, retaining larger and larger proportions of their primitive juices.

The hypothesis here suggested, namely, that the volatile hydrocarbons were distilled, as it were, from out the low-lying carbonaceous strata, into the pores and fissures of the overresting ones, receives strong confirmation from the fact that the elsewhere bituminous shales of the Silurian and Devonian ages, deep under the coal, are altogether as much dessicated and debituminized every where in the districts contiguous to the anthracites as the coal-beds themselves. Thus while the pies resting within the upper shelves of our hypothetical oven have been overcooked and rendered juiceless, the already more crusty ones lower down, and therefore still more effectually heated, are seen to be even more thoroughly baked and dried.

This generalization embraces, as a main element, a curious and beautiful law of structure of the whole American coal-field and its circumjacent regions. By giving due regard to it the reader will be greatly assisted in apprehending the full inductive strength of the theory. The prevailing structure alluded to is this: The entire Appalachian mountain chain, and the vast interior continental plain, or gentle slope, with an every where variegated and curved surface, stretching from these mountains to the great valleys or water channels of the St. Lawrence and the Mississippi, are, when structurally viewed, simply one grand broad area of approximately parallel elongated waves or undulations of all the rocky strata. Now the gradation in the quantity of the volatile matter in the coal is upon a general scale very nearly in proportion to a gradation which prevails in the openness or gentleness of these flexures of the crust. As al

There is indeed a law of gradation in the increase of the proportions of the hydrocarbons to the free or solid carbon, so universal and steady for change of locality, from the Southeast toward the Northwest for any traverse or section across the coal-fields, that it is practicable, within trivial limits of error, to foretell the quantum of coke or gaseous matters the coal will yield by merely knowing what we may term its geological longitude from the line or axis of total debituminization or complete conversion into anthracite. And it is pertinent to our argument here to note, that not only must we traverse across the first fields a given distance of many miles, before we can meet in the coalbeds themselves an assignable amount of the hydrogenous ingredients, but we must go a still further distance ere we encounter any marked indications or displays of the corresponding petroleums and carbureted hydrogens issuing from the general strata of the country. It is not in fact until we are almost half-way across the great Appalachian basin, in Pennsylvania and Virginia, where its coals are already more than half endowed with the full share of their bituminous matters, that we fairly enter for the first time on the wide territory so marked by tracts or belts of gas springs and petroleum; and it is only when we approach the western and north-ready stated, the anthracite or non-bituminous western margin of the vast basin, or get near the Alleghany River, and then enter Western Pennsylvania, Western Virginia, and Eastern Ohio and Eastern Kentucky, that the native or mineral oils and gases gush from the earth in their full abundance. How unmistakably does this curious gradation indicate that the coal measures at least, and we can not but include the other formations underneath them, must all have undergone at some crisis, or during some long period, a widely diffused and graduated or locally modified and attempered distillation or expulsion of the gaseous ingredients of the carbonaceous strata! This change was an almost total discharge of the volatile matters along the eastern most heated and convulsed zone, with a less and less complete displacing of them from

coal belongs to the most disturbed ranges of the Alleghany chain, and the basins where it has the least amount of gas, seldom more than six per cent., are those where the strata show the boldest flexures and the greatest dislocations. The semi-bituminous coals are embraced in all the wider, deeper troughs, in the undulated crust, which hold a line more to the northwest, but parallel to the anthracitic ones. In them the volatile matter in the coal is generally from eighteen to twenty per cent., and the strata or coal measures, ranging along the southeast edge of the great table-land of the Alleghany mountain are nowhere undulated in steep flexures or intersected with dislocations of magnitude. Still further westward, where the last really conspicuous great anticlinal and synclinal flexures of

mountain magnitude disappear, the coals contain | where they first came together under the potent of volatile matters as large an amount as thirty or spell of vegetable life. thirty-five per cent. Westward again of this line, It was obvious to us as a corollary of our as along the borders of the beautiful Monongahela theorem of the actions concerned in elevating River, where the stratification is almost horizon- and maintaining the great flexures of the crust tal, and there is a nearly total absence of faults, of the region we were studying, that the subterthe average is as high as forty per cent. While ranean heat connected with these stupendous still further on toward the western border of the long-ago-arrested waves must not only have been field, where the undulations in the rocks are ex-in past periods, but must now be, more transtremely broad and gentle, the quantity of vola- missible to the surface and more influential in all tile ingredients in the coal ascends to forty-five, its agencies along the anticlinals than any where and even to fifty, per cent., varying with local else throughout the country. In the spirit of circumstances. This gradation in the two con- this conviction W. B Rogers ascertained, in ditions, or the extent of debituminization and noting the geologic relations of the native therdegree of flexure, that is, of alternate uplift and mal waters (warm and hot springs) of the Apdepression of the strata, holds true, not only in palachian mountains, that they are almost invaPennsylvania, but by whatever lines we cross-riably coincident with the ruptures of the strata section or traverse the grand Appalachian coalfield, though its length exceeds eight hundred miles, and its maximum width is about two hundred.

along or near the anticlinal flexures or crests of the uplifted crust waves.

vol. xxxii.) that throughout the field he has examined few or no productive oil-wells exist where the strata are very nearly horizontal and comparatively destitute of fissures, although a large number of wells have been bored; and he alleges that "the most oil is found where the strata have been most disturbed, and where the fissures in them are most numerous." At an early period in the geological survey of Western Pennsylvania it was apparent that an anticlinal arching of the strata ranges under the localities which are now so rich in petroleum on Oil Creek near the Alleghany River.

More recently, Professor E. B. Andreys, of Marietta College, Ohio, has shown in a paper In accordance with the above-shown general on the rock-oil of that State and Western Virrelationship between the dissipation of the vola-ginia (see American Journal of Science and Arts, tile matters of the carbonaceous beds and the amount of flexure, and of internal fracture, which these beds have experienced, is the very striking fact, that throughout Western Pennsylvania, Northwestern Virginia, Southeastern Ohio, and Eastern Kentucky, or, in other words, throughout all the western borders of the great coal-field, where the general flatness of the coalrocks is only at wide intervals interrupted by narrow, but long and sometimes rather sharp anticlinal waves, the more copious emission of the rock-oil and the native gases is found to be chiefly restricted to the tracts occupied by the crests and sides of these local billows in the strata. It was long ago, before 1840, noted by my brother, Professor W. B. Rogers, in his geological survey of Virginia, and was observed and made known by myself in my own similar exploration of Pennsylvania, that nearly all the localities of abundant and comparatively permanent Artesian salt-wells or artificial brinesprings, with their almost invariable concomitants, the liquid and gaseous hydrocarbons, were situated upon, or nearly coincident with, the artificial archings of the strata. This was seen on the Kanawha by him, and on the tributary rivers of the Alleghany and Ohio by myself. At the salt-wells of the Big Kanawha (Charleston), the outflow of the inflammable gases was at one time so free in one of the borings, that the man- | ager of the works caused it to be collected and converted into fuel for evaporating the briny water along with which it ascended, as it does in so many of the salt-wells of the West. The gas issues from out the interstices and crevices of the rocks, coming up with the salt-water with which it has reposed for so many ages.

Strange accomplishment this of a long suspended connection; the carbon and hydrogen of some old sea-girt fields of vegetation, now allowed to extricate and crystallize the salt of the old ocean, which at such a lapse of antiquity once washed the precincts of the very marshes

Having adduced a sufficient array of statements to show where the chief districts of the petroleum are, the nature of the strata to which we ascribe its origin, and the conditions which determine its abundance, it only now remains to close this review of the phenomena by attempting a concise enunciation of the theory we have arrived at as to its sources and its distribution.

We are inclined to attribute the petroleum and its associated hydrogenous gases to a fermentation and distillation, by subterranean heat, of the hydrocarbon elements resident in all the carbonaceous strata underlying the rock-oil region, that is to say, impregnating the Silurian black slate (Utica), the Devonian black shales (Marcellus and Genesee of New York), and the coal seams and carbonaceous shales of the bituminous coal measures. Indeed, we are disposed to assign the oil and gas to the lower-seated Silurian and Devonian deposits almost exclusively, and for these strong reasons: First, that they come forth, and very abundantly, in large districts far remote from any tracts of the coal formation, and where those inferior rocks are the only carbonaceous ones which underlie the surface. Secondly, that a like discharge of petroleum and combustible gases occurs in none of the other coal-fields of the earth, even where their coal-beds are notoriously bituminous and

All

Aunt Dilly caught the look; for whatever had become of the charms of youth her eyes and cars had lost none of their original keenness.

"Don't you believe me?" quoth she, giving a hitch to the left shoulder of her dress. Then she made several more short nods, and smiled to herself as if at old memories. "Didn't you never hear me tell about Linus Leach and his cherry-party?" asked she, presently.

dangerously full of fire-damp. Thirdly, there | chin, and wondered within herself if they were are some differences, so the chemists inform us, always so long and sharp. between these native hydrogenous products and the genuine coal-oils and their resultants, procured by artificial methods of separation. these facts awaken a strong surmise, confirmed by the obvious diversities in the specific gravities and other qualities, and by the excessively offensive and non-bituminous odors of some of the petroleums of the countries exterior to the coal-field, such as that of certain localities in Canada, that the greater portion of the oil and gas is really derived from the marine animal carbonaceous shales, and not from the vegetable beds of coal and their coaly rocks. The occurrence of so many symptoms of rock-oil within the limits of the coal-fields, now replaced by such a multitude of productive oil-wells, tells for almost naught against this hypothesis, as it is known that the Silurian and Devonian black carbonaceous shales pass under all the northwestern and western districts of the coal meas

ures.

My view of the process of extrication of the petroleum from the lower strata and of its accu mulation in the pores, crevices, and joints of the upper ones, is simply this: We may conceive that during the epoch, or the perhaps successive epochs, of the uplifting of all these water-buried and water-side sedimentary strata, earthquake pulsations and other undulations of the crust formed and fixed the flexures in the strata which we have described, and that during the earthquake oscillations, and even after their cessation, a copious amount of the highly-heated subterranean steam, the constant attendant upon earthquakes, heated the strained and ruptured rocky beds, dislodged their more volatile constituents, and carried or distilled these latter, one portion into the atmosphere and a residuary part into the interstices of the overlying cooler and less fractured strata. Upon this hypothesis we see how in those belts of the Alleghanies where the crust was most convulsed and the rocks were most contorted and highly heated, the coal-beds were actually coked into dense anthracite, and how further from the lines of maximum subterranean pulsation and steaming of the rocks the volatile matters below the surface were progressively less expelled, till entering the petroleum districts the crust movements and warming were so moderate that they only sufficed to displace the tarry and gaseous matters from the underlying beds, to leave them, at least in part, in the cavities and cells and fractures of the overresting strata.

"What was it, Aunt Dilly?" returned goodnatured Bessy, who had heard the story ever since she was a small girl often and often.

Aunt Dilly threaded her needle complacently. "Linus was some older than I was, but he took a great shine to me, and I expect I was well-looking and appearing as any of them. I could dance like a top, too, and I was a good deal sought after for a partner at all the balls and parties," said she, frowning with an air of superiority at Clara. "Linus paid me a sight of attention, and I expect nothing but he would have made me an offer if I hadn't been so offish. He made me a present of the first umbrella that ever was brought into this town, and I was always sorry, if he would give it to me, that it hadn't been silk. He lived up in what is Lawriston's Mills now, on the old Weatherbee farm, and it was a grand, good fruit-place, I can tell you.

"One time he invited all us young folks there to eat cherries. He had a noble cherry-orchard, and he went and cut down some of the best trees, so we could pick the cherries handy and at our ease. Then if he saw any body getting an uncommon nice bunch he would say, 'No, no, that is for Miss Dilly! Let Miss Dilly have that!' Molly Holister was a real hector, so she would try to get the best ones on purpose to plague him; then she would ask, 'Why couldn't she have them? She wanted good cherries as well as Dilly!'

"Yes, I suppose I might have gone up there to live if I had run of that notion; but Leach was as gray as a rat then, and he wa'n't considered over-bright neither. So I didn't give him no encouragement, and he got to going with Hepsibah Hitchcock after she come in town and set up tailoring; and finally he didn't marry nobody, but went out West and died there."

"But didn't you have an offer from any body?" queried little Lucy, who sat on the floor with her lap full of kittens, greedy for any thing which sounded like a story.

"Tchis!" ejaculated Aunt Dilly, by which she meant to say Yes. "I had offers a plentyor might have had if I'd wanted them. The young fellows understood that I was smart to work besides being lively company; and I didn't pass for any body's fool, I can tell you. I suppose likely I might have married to Cephas Johnson if I'd been a mind to. He run after

"No indeed; I guess not!" exclaimed the old lady, emphatically snipping off a thread as she thought of the manner in which the hopes of her retinue of admirers had been cut off. "Tell more," said Lucy, stroking the sleep-mouth contemptuously. ing kittens.

"I expect likely I might have been keeping house for Dr. Dillingham to-day if I had been so inclined," asserted Aunt Dilly, looking about her with an air of triumphant defiance.

"Pears to me you are over-young to be filling your head up with beaux and offers. When I was your years nobody never heard such talk from me, and I should think you would be bet-. ter employed studying your book than in inter"Why, Aunt Dilly, I didn't know you ever rupting older people with your saucy questions." even spoke with him!" exclaimed Bessy.