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Geological Reconnoissance.

We

[25th CoNG. 1st SESS.

stones were produced, there is much ambiguity. stones of British geology, have their equivalents in this counknow, however, that mineral springs, both thermal and try. In nothing is the analogy in the two hemispheres more cold, deposite carbonate of lime in great quantities, as they constant than in the general character of the transition and come in contact with the atmosphere. The prodigious grauwacke beds, even to the chloritic nature of some of the beds of the old red sandstone; the same conformity also deposites of this character from a cold mineral water, in the can be asserted as to their fossiliferous character. It is true Sweet Springs valley, in Virginia, which presents one of the most rare geological phenomena, the no less interesting that in the north of England the grauwacke is found lying travertino deposited by the Hot Springs of the Washita, in at a great inclination, and upset on its edges, with conArkansas, both of which localities I visited this last year, glomerate or old red sandstone unconformably upon them; and similar phenomena in various parts of the world, ren. showing that this last, not being affected by the movement der it quite possible that some extraneous calcareous de- which had disturbed the grauwacke, or having been deposites, lying amidst the primitive rocks, have come from posited since that movement, was not, in the estimation of the central parts of the earth, in a state of aqueous solution, some persons, to be classed in the same division with the and have subsequently received their high crystalline char- grauwacke. By these the grauwacke was considered the acter from being in contact with ignigenous rocks in an in- limit of the transition series; but in countries where the candescent state. With springs of such a character in ac-old red sandstone and the grauwacke laid conformably on tion, the animals of those times could be at no loss for calcareous matter in favored localities; and, in that greater portion of the aqueous surface where lime was wanting, we can readily believe that the Creative Power might give a benevolent existence to countless myriads of those gelatinous animals which fill some tropical seas in our own days, and which, having no solid parts, have left no vestige of their existence behind them.*

Perhaps the time has arrived when the term transition should be limited to the argillaceous masses in question. The connexion, however, between them and the shales and slates, and other beds which succeed them higher up in the geological series, has induced some geologists to consider all the members of this connexion, including the bituminous coal measures, as belonging to one natural group. Yet I cannot but suppose that a series of deposites extending to thirty or forty thousand feet in thickness on this continent, and probably to an equal amount in Europe, will, when it has received an examination consistent with its great importance, be ultimately arranged in a more lucid and characteristic manner. The lower slates, the flags, the grits, and lime

* Professor Agassiz, a distinguished naturalist, who appears at present to lead in fossil ichthyology, does not find fish decidedly carniverous before the period of the carboniferous limestone, that is to say, fish are not provided with targe conical and pointed teeth; those of later periods appear, however, from their teeth, to have been omniverous The investigations up to the present moment all point to the conclusion that organization was upon a low scale in the transition period. M. Adolphe Brogniart the able author of the Historie des Vegetaux Fossiles, and to whose genius and industry we mainly owe the infor mation which has been produced respecting fossil vegetables, whilst he has enumerated 258 species found in the coal deposites, only finds fourteen in the transition series, and these, if I remember aright, (not having his work here,) all cryptogamous plants. To these facts, if we add other considerations, such as the great uniformity of the genera in the inferior rocks of both hemispheres, where trilobites, producta, spirifers, and othocera are the characteristic organic remains, and the curious fact that of the whole number of species of fossil coal plants found in North America, more than one-half have been found connected with the coal fields of Europe--a greater proportional simili tude than exists among living plants-we can scarcely, in the present state of geological information, assent to any theory of causes now in operation," for fossil nature, which excludes a law of progressive development, under which we see the fitness, for all this uniformity, of some common cause, extensively operating as thermal waters, even upon the oceanic scale, may be supposed to have done.

The section which accompanies this report, traces in an imperfect manner the transition rocks from the vicinity of Harper's Ferry, on the Potomac, to the Cumberland mountains in Tennessee. I could not, with satisfaction to myself, enter, upon this occasion, into details re specting the fossils of the transition and grauwacke rocks of North America which I have examined: they have accumulated greatly upon my hands, and would furnish materials for an important work, that would require a great devotion of time, and incessant labor. My friend, Mr. Murchison, late President of the Geological Society of Lon. don, who has distinguished himself so greatly by his researches in the superior beds, has been much occupied for the last four years in a great work, to contain numerous plates of unpublished fossils, illustrative of the "stratified deposites which connect the carboniferous series with the older slaty rocks" in England and Wales, and which will give a singular impulse to investigations of the transition beds. Mr. Richard C. Taylor also, who well deserves the high reputation he has acquired as a geologist and mineral surveyor, is about to publish a very important account of the transition beds, which he has extensively examined in Pennsylvania. I feel confident that the comparative views we shall Boon be able to bring forward between these analogous deposites, will extremely strengthen the opinions I entertain of the strong generic resemblances between the organic forms of the transition period in both hemispheres.

each other, the argument was equally strong for arranging the superincumbent formation in the same series with the inferior one. In the United States we find them both upset on their edges, at very high inclinations, and therefore no sufficient ground upon that score is presented here for placing them in different divisions.

But there is one general character which is common to many beds lying much higher up in the series, and that is fossil coal; and here we find another circumstance, which induces some geologists to class the whole together as a coal-bearing series. Hereafter it is possible that the wide difference between the non-bituminous and bituminous coals may suggest a permanent character for the arrangement of the coal-bearing rocks.'

In all essential circumstances, the features which mark the structure of the coal bearing series of rocks in Europe are found here. In the the grauwacke we have beds of limestone, derived, for aught we know to the contrary, like the statuary limestone in the primitive series, from solutions ejected from below, alternating with schistose In these and sandy beds of probable mechanical origin. limestone beds we occasionally find, as in Europe, increased numbers of animal remains, and cognate in their relations, such as the flustra, the trilobites, &c., on the calcareous plates from Dudley, which are often identical with those of the Alleghany ridges.

In the lower parts of this series, in Europe, are found

The very general concurrence in the opinion that coal beds may be a residuum of vegetable matter, appears to have induced many geological writers to assume the same origin for all carbonaceous deposites. The prevalence of vegetable impressions on the shales connected with the coal in some localities, seems to them to be sufficient ground for the assumption. I have seen many of the non-bituminous varieties in place in this country, which appeared to me to justify a scrutiny into that belief. Anthracite coal is found in the lower slates, which may be said to be the commencement of the transition series in many parts of North America, yet fossil plants are not found in some of them, and they are very rare in the transition rocks of all countries; a fact which detracts from the opinion that it is of vegetable origin. However reasonable may be the inference arising from the convertibility of vegetable matter into lignite, jet, and bituminous fuel, that many important heds of coal have a vegetable origin, yet due weight should be given to some circumstances from which a different origin may be in ferred.

In the beds of plumbago which lie in the gneiss at Sturbridge, Massachusetts, the mineral is nearly vertical in the rocks, like the micaceous oxide of iron in other situations: this graphite is carbon. combined with a small quantity of iron finely disseminated through it. At Worcester, in the same State, nearly the same mineral, in a semicrystallized state, occurs in the mica slate, but here it is called anthracite coal, although it has been ground and sold for plumbago. In the lower slates of Rhode Island, the same mineral occurs with a diminished specific gravity. Near Poughkeepsie, on the Hudson, I have seen veins of anthracite in the lower slates, from half an inch to two or three inches broad, rising, like metallic veins, to an inclination of 70°. In Pennsylvania we have heavy beds of anthracite in the grauwacke, which are non-ferruginous, and others which are slightly bitu minous. These localities show a progression in the quality of this mineral not at all consistent with a vegetable origin. Its lowest beds are metalliferous, and its specific gravity decreases as it rises in the series. The slaty shales which usually accompany coal, cannot be said to be an integral part of it, but may owe their origin to a mechanical deposite modified by the high temperature of the carbonaceous body, and which favored the production of plants now only found in low latitudes. The slates of Rhode Island, which accompany the coal, contain talc, and abound in asbestos.

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those non-bituminous coals now generally known here under the name of anthracite; and in this country we find the same carbonaceous matter distributed through the whole system of Alleghany ridges to the most western counties of Virginia, where the inclined rocks begin to give way to the horizontal formations of the Cumberland range of mountains. Higher up in the series, and reposing upon the vast deposites-in this country immense-of carboniferous limestone, and millstone grit and shale, where these minerals are not replaced by more complex deposites, we find, in Europe, the great productive beds of bituminous coal, exactly as they are found in some parts of this country, lying amidst shales and sandstones, often of a friable structure, and abounding in mica. The fossil plants, too, are nearly related in both countries, and some identical. It is true the coal in some instances in Europe, as at St. Etienne, in France, is found resting upon the naked granite, which is exactly the case with the coal measures of Chesterfield, Virginia; this lies in troughs of granite the edges of which crop out above ground, showing the exact limit, in some instances, of the coal field. Nor is it to be supposed that, because intrusive rocks of a granitic character have appeared subsequent to fossiliferous rocks, the base of these coal measures has thus been formed, and contemporaneously with the carboniferous deposites which repose on them, for the Chesterfield granite is a well-defined and beautiful porphyritic granite, with its red crystals of felspar, precisely resembling that of Shapfell, in England, and forms part of that extensive granite formation which looks at the Atlantic coast from the cast flanks of the Blue Ridge, and which I have traced far into Alabama.

Nor is that extraordinary coincidence in both hemispheres, in the state of the beds of the carboniferous limestone, to be overlooked. Some of them, teeming with the imbedded exuviæ of animals; others conspicuous for the plates and irregular masses of chert, resembling the flint as it is seen in the chalk beds of Europe; whilst both alternate with beds of compact limestone, of different degrees of crystallization, and non-fossiliferous. Those who have seen the encrinital and other beds of the European carboniferous series, may see the same thing repeated in various parts of this country in the western parts of the State of New York; at the Helderbergh mountains; conspicuously in Tennessee, in Kentucky, and the State of Missouri. Here, in some instances, the rocks appear to be composed entirely of organic remains, whilst others seem to have been deposited so rapidly as to have given no time for their production. It is at this period, however, and amidst this profusion of calcareous matter, that such immense numbers of testaceous animals of the same kinds have existed in both hemispheres.

In the carboniferous limestones of Tennessee, Kentucky, Indiana, Illinois, and Missouri, I made very rich collections of fossils, many of which are identical with European specimens; indeed, it is probable that most of the European genera will be found there. There are, however, great numbers of species which differ from those found in Europe, some only slightly, whilst others again are quite new. My scientific friend, Dr. Troost, professor of geology at the University of Nashville, and geologist to the State, has discovered some interesting fossils, which, it is to be hoped, he will soon find leisure to describe. I saw in his cabinet an asterias, found in the carboniferous limestone, having five rays, but having lost the spines and epidermis. The following are a few of a very long list of European cognate fossils I brought from the States above mentioned: Orthocera, encrinites, producta, spirifers, plagiostoma, natica, ampullaria, delphinula, euomphalus, turbo, pentremites, trilobites, asaphus platycephalus, hamites, tere bratula, bellerophon, nautilus, cardia, trochus, turbinolia, cyathophyllum, astrea, stromatapora, calamopora, manon, eschara, with an innumerable quantity of the zoophytes described in Goldfuss. Although these fossils are not identically the same with their equivalents in Europe, yet many of them are strictly so, and in all cases I would assert the generic resemblances to be stronger than the specific differ ences. On this continent, where the carboniferous limestone extends uninterruptedly for more than one thousand miles, we find an equal amount of generic resemblances and specific differences, notwithstanding that the causes which produced the beds were obviously cotemporaneous and the same; and it is certain that the specific difference between the most powerful species of living animals here, and those in transatlantic countries, seems to be much greater than that which prevails amongst the fossils of the two hemispheres.

In examining the structure of the transition series of rocks, we perceive that it partakes largely of a mixed character, both chemical and mechanical. Many circumstances, presenting themselves under various aspects in different and distant localities, point to a direct central origin for the limestone beds of the carboniferous limestone, and for those siliceous solutions which have frequently changed the character of their fossils, and sometimes replaced the calcareous constituent throughout the whole beds; a fact observed by myself in the State of Missouri, where certain oolitic beds of the carboniferous series-and which occur also near Bristol, in England-are entirely converted into siliceous matter. The presence of bituminous matter, too, in some of the fetid beds of this last series, would give strong support to the opinion that some coal beds may have been the result of outpourings of bituminous matter, and not of vegetable decomposition. The fetid beds of the western part of the United States are in some places so impregnated with bitumen, that when the limestone rocks of the canal were blasted at the falls of the Ohio, the bitumen oozed from the rocks in such great quantities, that more than a gallon a day was collected by the workmen. I have myself drawn bitumen in considerable and unusual quantities from these rocks.

One of the most remarkable geological features of this continent is the vast extent of the carboniferous limestone. I have traced its eastern border-conforming to the course of the other mineral formations east of the Mississippi-more than one thousand miles running to the west of south, from the State of New York to the thirty-fifth degree of north latitude in the State of Alabama: the course is then changed, and lies to the north of west, leaving Little Rock, on the Arkansas, about thirty miles to the south, and disappearing between five and six hundred miles from the Rocky Mountains. This deposite extends, uninterruptedly, a geographical distance of at least 1,500 miles from east to west, underlying portions of the States of New York, Pennsylvania, Ohio, Indiana, Illinois, Missouri, and the Territory of Arkansas, on that line. In Tennessee, Kentucky, Virginia, and Maryland, it is bounded by a line of which the Cumberland mountains form a part. In the plains through which the Mississippi flows, and which include the Illinois prairies, it appears like a continuous floor, forming an almost unvarying flat; for although the superficial level is irregular, that of the calcareous formation, lying beneath the arable soil, seldom seems to change its elevation materially.

In other parts of the area covered by this deposite, there have been extensive denudations of the beds, whilst in some of the Western States broad table lands of it still remain, and which are occasionally covered with sandstone, as is the extensive table, forty miles broad, of the Cumberland mountains as far as the begining of the descent down to Sparta, where the sandstone contains indications of bituminous coal. From hence to Nashville, about eighty miles, the country descends over various beds of carboniferous limestone: that which immediately succeeds to the above-mentioned sandstone has a marked oolitic structure, and is about two hundred feet thick. The beds are all horizontal, and many of them abound in organic remains, whilst the chert in the seams takes an agatized form, with a chalcedonic botroidal appearance, such as I have seen in similar situations west of the Mississippi. The lowest point at which I had an opportunity of examining this series of the carboniferous limestone was at Nashville, on the Cumberland river. The town is built on naked beds of horizontal limestone, some of which are loaded with fossils. The beds through which the river has cut its channel, and which appear in various parts of of the neighboring country, vary a good deal in their crys

*

*Of which the pentremite, according to Dr. Troost, is the characteristic fossil.

Geological Reconnoissance.

talline structure, and in their organic remains. The Cumberland being unusually low, I had a favorable opportunity of examining some of the inferior beds, which were of a dark bluish gray color, having a structure between that of primary and compact limestone. These rocks occasionally abound with nodules of siliceous matter, resembling chert, black outside, grayish within, which seems to have been infiltrated into cavities once containing organic matter. They are frequently covered with fucoidal strings, and numerous zoophytes, of which the characteristic marks are obliterated; have rounded surfaces, from aqueous attrition, the calcareous matter having been rubbed away, and the cherty matter left in relief, as I have frequently observed on the rocks on the right bank of the Mississippi. Higher up in the formation, the beds contain cavities, in which or ganized bodies appear to have been imbedded, and many of which are now filled by interesting accidental minerals. Their walls are generally lined with carbonate of lime, upon which beautiful crystals of strontian, of a fine sky blue color, with intermediate shades, sulphate of barytes, fluate of lime, fibrous and snowy gypsum, and sulphuret of zinc in rare crystals upon brown spar, are often found: the same accidental minerals are found in the horizontal carboniferous limestone in the State of New York, and in other localities. This limestone, when rubbed, smells faintly, like bituminous linestone, although it lies much beneath any indications of bituminous coal which have been yet observed. In the banks of the Cumberland, Dr. Troost pointed out to me a conglomerate bed of dead shells, where pairs of bivalves seldom occur. The organic remains of this bed are generally fractured, and often much comminuted. It lies between two strata of compact limestone, and in some places is fifteen feet thick, whilst in others it thins off to one or two feet, and is often entirely wanting. Above all these beds is a stratum of coarse granular limestone, covered almost entirely with strophomena rugosa, a well characterized fossil.

An

Harpeth ridge rises much above the level of Nashville, and is remarkable for containing beds of a greenish color, derived from chloritic matter, as well as a bed of slaty clay, very bituminous, with reniform ferruginous masses. encrinital bed of limestone near the top, alternating with sandstone, is covered with an argillaceous sandstone. The whole structure of this ridge bears a strong resemblance to the country described in Lieutenant Colonel Long's return from the Rocky Mountains. I have recognised these beds in many distant parts of the country, and have frequently fallen in with the same stratum of bituminous shale. But as the details of the geology of this part of Tennessee will be given to the public with great care by Dr. Troost, who has made himself complete master of them, I shall proceed to give a sketch of the structure of this great deposite of carboniferous limestone, as it is exhibited in the descent of the Cumberland river from the falls to Nashville, a distance of about three hundred miles. This will show the true relative position of the beds of this great formation to each other, as the river, in its course, has opened them all up from its source in the high table lands, for a depth of at least 1,500 feet, to where the Cumberland enters the Ohio. The true place of the bituminous coal beds of this group will be here seen, so that those who take the trouble to make themselves masters of the distinct mineral and fossil characters of each bed, and the order of their succession to each other, can always form an accurate judgment whether any particular district is above or below the coal. upper part of the profile section now to be described, corresponds in so many important particulars to those characteristic beds which, in Europe, frequently divide the coal measures from the carboniferous limestone, that I have not

The

* Vide James's Account of Long's Expedition, vol. 2, p. 160,'et passim.

VOL. XIV.--A 42

[25th CoNG. 1st Sess.

hesitated to recognise in it the equivalent of the formation called millstone grit and shale.

The Cumberland at the falls, in Whitely county, Kentucky, has worn its way through a quartzose conglomerate, united by a siliceous and argillaceous cement, to the depth of at least five hundred feet, and continues to flow over it for some distance beyond the falls. Pursuing its way, it next cuts through a bed consisting principally of shale, about two hundred feet thick, in which are three horizontal good veins of bituminous coal, each from three and a half to four and a half feet thick. The river runs on the bottom of this bed about three miles below the mouth of Laurel river. The banks of the river continue to expose the coal veins until seven miles below Rock Castle river; but here the Cumberland has cut into a bed of compact limestone, with an oolitic structure about three hundred feet thick: to this succeeds a series of horizontal beds about two hundred feet thick, which, at the mouth of Big Indian creek, is exposed in the banks, together with a seam of bituminous shale, the equivalent of that at Harpeth ridge, and which is here twenty feet thick. At this place the river has cut into the inferior beds of limestone which are found at Nashville; these may be estimated at about three hundred feet thick down to the junction of the Cumberland with the Ohio. At Burkesville the river has worn its way about one hundred and fifty feet into this last series of beds. A perpendicular section of these rocks would appear thus: Conglomerate of millstone grit, 500 Shale, with coal veins, Compact limestone,

Carbonifer

ous limestone.

Horizontal beds,

Bituminous shale, Lower series of beds,

200

300

200

20

300

1,520 feet.

During my late tour I had occasion to examine the bituminous coal beds in various parts of the State of Illinois; and in the bluff, distant about seven miles east from the city of St. Louis, a fine vein about eight feet thick is opened for the consumption of the city. This bluff, which is near one hundred feet high, is the termination of the level of the prairies of Illinois to the west, and bounds a rich, swampy tract of land formed of black vegetable matter--once overflowed by the waters of the Mississippi-now called the American bottom.†

The coal in the bluff opposite St. Louis lies between ledges of limestone, in a perfectly flat seam, measuring about eight feet to the floor. From the stratum of compact limestone superincumbent on the coal, I obtained a fine productus and a terebratula; but in the slaty shale above the coal, which is loaded with sulphuret of iron, I could not obtain the slightest impression of a plant. It is the same with the coal on the western side of the Mississippi; nor does any part of that extensive carboniferous country present a basin-like appearance, into which trees or plants could have been washed, or in which aquatic plants could have adequately grown. Many who are led by practical observation to assign a subterranean origin to the extensive floors of limestone on which the coal reposes, might, also, probably indulge the idea that these coal beds may have had a similar origin, fortified as it is by the existence of bituminous matter in the beds of limestone, and by many other considerations present to an observer.

Extensive as this immense field is, where bituminous coal is found deposited in so many places, yet it by no means represents the geological conditions under which bituminous coal is deposited in other parts of North

*I am indebted for this section to a reconnoissance made by Messra. Stansbury and Baily, by order of the Topographical Bureau.

Thirty miles south of St. Louis I recrossed the Mississippi, fand found a continuation of this bottom about six miles broad, over which I walked to the bluffs.

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America. In the granitic trough of Virginia, the coal lies amidst shales and loose sandstones of a micaceous character, the superincumbent shales affording fine specimens of vegetable impressions. In the great bituminous coal measures of Western Pennsylvania, separated from these last by the primary and easternmost chain of the Alleghany mountains, the coal is found amidst similar but more indurated sandstones and shales, high up in the hills, which have been truncated and furrowed out into valleys, so that the continuity of the veins is found without difficulty in distant isolated hills.

It may also be instructive to observe here that the castern coal-field of the Southern States, with which we are acquainted in Virginia and Alabama-in the former of which States it has already become a source of great wealth, giving constant employment to locomotive power and shipping-may reasonably be inferred from some known partial indications to be continuous between those points. I can confidently assert, from personal inspection, that there is a very promising line of continuity between those extreme points; and that bituminous coal, of a very fine quality, may reasonably be expected to be found in situations where it does not crop out on the surface. As an evidence of the confidence which may be placed in geological indications, I consider it important to mention, in a brief manner, a coal mining operation now conducting in England-and which had just been commenced during a visit I paid that country in 1826-upon the sole ground of an entire confidence placed in geological principles, and without any indication whatever of coal cropping out on the surface. shaft was sunk at Monkwearmouth, near Sunderland, in the county of Durham, through a group of calcareous rocks, which were supposed, from the immutability which rocks are believed to preserve as to the order of superposition to each other, to overlie certain coal veins existing in contiguous parts of the country. The shaft was sunk 344 feet beneath the surface before any coal was found; they then reached a small seam of one and a half inches in thickness.

A

*This chain of primary rocks, which traverses the United States from their northern boundary to the western termination of the highlands of Alabama, receives various designations in some of the States, which occasions some confusion in the maps, and consequently to travellers. The true structure of the general series of the Allegany chains or ridges, which are numerous, has been hitherto misunder stood, and, having been occasionally embarrassed when conversing on the subject in the country, I avail myself of this opportunity to cor rect this misapprehension.

The primary rocks which are seen on the Atlantic coast, occasionally covered by the subcretaceous and tertiary beds, extend west into the interior until they terminate in the chain of primary rocks above alluded to, which coming from the north-northeast-the general mineral direction on this continent-is cut through at West Point, in the State of New York, by the Hudson river, and passing through Pennsyl vania and Maryland into Virginia, is there called the Blue Ridge, from the bluish tint which is reflected from it. Beyond this ridge, to the west, the numerous ridges and outliers-the most conspicuous of which are parallel-belong to the transition and secondary rocks. These have various local names; but the most important of these sedimentary ridges is one called the Alleghany mountain, which forms the eastern boundary of the counties of Randolph, Pocahontas, and Greenbrier, in Virginia, and then deflecting more to the east with irregular flexures for some distance, at length butts up against the primary chain near the Southeast corner of the county of Botetourt. Here the primary chain divides into a fork, the westernmost prong of which, called the Iron mountain, forms the western boundary of the county of Grayson, and the eastern prong the eastern boundary of the same county, so that the county of Grayson, and the new county of Floyd, He mainly between the two prongs. But the country people, not aware of the difference between sedimentary and primary rocks, suppose the eastern prong to be a prolongation of the sedimentary ridge called the Alleghany moun tain, and give it that name, which obtains in many of the maps, whilst they call the western prong, or Iron mountain, the Blue Ridge. In one sense this incorrect designation is not without a reason, for this supposed continuity is the great water shed of the whole country, the sedimentary part throwing down some of the waters of the Kanawha river to the west, and the waters of the James river to the east, whilst the primary portion sends down the head waters of New river to the west, and those of the Roanoke to the east. It will be apparent, I think, to every geologist, that as this primary chain is the true boundary of the sedimentary rocks lying west of it, and forms so important a fea ture in the mineral structure of this country, it should receive a clear geological designation; and as it looks upon the Atlantic coast in its whole course, I shall propose the game of the ATLANTIC PRIMARY CHAIN.

This occurred in 1831, after encountering incredible difficulties in stopping an influx of water that had frequently almost overpowered them. They proceeded to a depth of one thousand feet, when it became necessary to invest more capital in pumps of greater capacity, and this without meeting more coal. But the proprietors had confidence in their operations, and, amidst the loudly expressed doubts of many of their friends, persevered until, at a depth of 1,478 feet below the level of high-water mark, they reached a very valuable seam of fine coal, and are actually now carrying their shaft to a depth of one thousand eight hundred feet, in order to reach a vein of coal long worked in other situations, and which they are confident will be found within that depth. This vein, when reached, will repay all the outlay of capital, and become a source of great wealth. In whatever manner I have been able to regard the carboniferous series of rocks in the United States, however dissimilar the mineral structure of its beds and its levels may occasionally be, yet I have not been able to resist the impression, and could demonstrate, if this were the proper occasion to do so, that the general structure of the series is a fair equivalent of that in Europe, and has probably been produced by the same causes.

The next rocks in the geological series are those which lie immediately above the coal measures, and belong, by common consent, to the secondary. This division includes a very important number of beds which have never been found in the United States; we may possess the equivalents of some of them, such as the muschelkalk of the Germans, and the red lands of Devonshire: further investigations will probably determine that point; but the geological investigations, which have been made east of the Mississippi, have scarcely left us any ground to expect that any of the members of what is called "the oolite formation," from beneath the purbeck beds to the lias inclusive, will ever be found on this side of that river. Perhaps this cannot be asserted with equal truth of that group of rocks which lies between the coal measures and the lias. This group, usually characterized by the formation called new red sandstone, has been always considered an important depository of gypsum, as well as the source from whence salt brines have been derived in many parts of the eastern hemisphere. The brines of this country are derived from so many sources, that this group is by no means entitled to be considered their sole geological depository in the United States. The mineral waters of Saratoga, in the State of New York, and other mineral waters obtained at Albany, in that State, are very strongly impregnated with muriate of soda, containing upwards of sixty parts of that mineral, and these waters rise through the lower slates which repose upon the primitive rocks. The salt wells of Kiskiminetas, in the State of Pennsylvania, are fed from beneath the carboniferous limestone. I have been furnished with borings effected in that part of the country, which have been extended to about seven hundred feet, and have passed through important veins of bituminous coal. These borings gave the following vertical section:

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Geological Reconnoissance.

tion to its valuable deposites of gypsum, the powerful flow of the brine, its unlimited quantity, or the structure of the superficial beds, is more interesting than any one of its class which I have ever seen. I could name other localities resembling these. On the other hand, the salt wells of Salina are fed from a deposite of a marly character, which occasionally has a strong resemblance to some members of the new red sandstone group of Europe. This great branch of geology has hitherto received very little attention in this country.

Of the superior portion of the secondary rocks, we possess some important members. The upper beds of the chalk group have not yet been seen in North America, at least not with the same mineralogical character, nor with seams and nodules of flint similarly disposed; but many of its inferior beds are found in a very irregular and ancient littoral line from about 40° north latitude, in New Jerseyand perhaps about 41° 20′, underlying the tertiary beds of Martha's Vineyard-to the thirty-second degree of north latitude, in Alabama. Pursuing a sinous course thence towards the northwest, it reappears on the west side of the Tennessee river, at about 35° 40', and by intermediate points I have traced it to 33° 45′ in Arkansas. Further west it is seen near the Kiamesha, and at various points up the False Washita, to the eastern limit of the sandstones which are found on the eastern slope of the Rocky Mountains; thence it deflects to the north, and runs up to the Black hills, which, compelling its course east of north, it crosses the Missouri north of the forty-third degree, and probably terminates south of the Mandan country, between the Black hills and the highlands of Coteau de Prairie. Indications of this ancient shore, which appears to have had for its limit that general water level of the sea which deposited the lower chalk beds, will, no doubt, be hereafter discovered up many of the rivers of this continent.*

Within it are contained both the lower beds of the chalk group and the representatives of the tertiary group which have received so much attention in Europe.

From the examinations I made when in the State of Alabama, and from the details which were given me of borings for fresh water through the calcareous deposites to a depth of five hundred feet, as well as from the general trending of the eastern slopes of the Atlantic primary chain, I consider it as most probable that they all lie upon the primary floor, which extends to the ocean, and which shows itself at the falls of all the principal streams.

The subcretaceous beds in Alabama extend about one hundred miles south from Pickens county, and appear to be bounded by an irregular line running southeast by east to the falls on the Coosa. Above this line, to the north, the bituminous coal comes in, lying, like that of Virginia, on the primary rocks. The tertiary strata are found south of the subcretaceous area. The Alabama river, with its tributaries, the Tombeebee, the Black Warrior, and the Cahawba, cuts through these beds. At Prairie Bluff the Alabama has laid open rich deposites of the subcretaceous strata, from whence I brought ammonites, baculties, turritella, scaluria, gryphæa convexa, exogyra costata, and numerous other fossils belonging to these beds. Further to the south the river at Fort Claiborne has cut through the tertiary strata. +

If the mineral character of these beds, from their occasional dissimilar appearance, could raise any doubts as to their equivalency, the decided character of their fossils would certainly remove them. The agreement of the fossils found in some of the beds in the State of New Jersey with those of the green sand and associate beds in Europe,

I picked up two or three valves of gryphiæa costata on the banks of the Ohio during the last summer.

+ Mr. Conrad has personally examined the Alabama beds with his usual judgment.

The fossils of these beds have been beautifully figured by Mr. Lea, in his "Contributions to Geology."

[25th CoNG. 1st SESS.

when considered in connexion with their geological position, can leave no doubt in the mind of an experienced geologist, of the first being true equivalents of the last, and this was announced several years ago."

The tertiary strata approaching the top of the geological series, and coming so near to the present order of nature, we may reasonably expect the fossil remains contained in them to be more or less specifically allied to existing shells. This has been shown to be extensively the case in Europe, by Mr. Lyell and other writers. That eminent geologist has divided those strata into periods characterized by the proportion of recent and extinct shells found in the same beds. It has resulted from this manner of investigating the subject, that, in the beds nearest the existing order of nature, shells now living are found mixed in the greatest proportions with those which are extinct; and that in the lowest beds of the tertiary strata the proportions are nearly inverted, showing a systematic progression of species, conforming in this to the progression of organic nature in the older geological formations. The tertiary deposites of the Atlantic States are very numerous, and extend far to the South. Wherever I have found the subcretaceous beds, I have found some of the strata of the tertiary. I found the beds of Mr. Lyell's Eocene period in various parts of the Territory of Arkansas; and in the very great number of tertiary beds which I have seen betwixt the Delaware river and that Territory, I am disposed to believe the equivalents of Mr. Lyell's periods may all be found. From some of these localities I have collected great numbers of living species, which yet partially retain a fine color. The Choptank river, in Talbot county, on the Eastern Shore of Maryland; the counties of Prince George, Charles, and St. Mary's, in Maryland; the counties of Hanover, York, and especially of Prince George, in Virginia, present admirable localities for those who are disposed to examine the relative age of these beds; indeed, all the Southern States, and conspicuously that of Alabama, present an extraordinary field for inquiries of this nature, the tertiary strata covering a prodigious area towards the Atlantic. In Prince George, Virginia, the tertiary strata will probably be found to rest upon the subcretaceous beds; and it is interesting to geologists to note, that the bituminous coal beds of Chesterfield county, which rest upon porphyitic granite, are the limit of these calcareous strata, just as the bituminous coal of Alabama is the limit of the subcretaceous beds in that State. +

* Dr. Morton, in his instructive Synopsis, states that " Mr. Vanuxem was the first to detect the analogy between this deposite (subcreta. ceous) and the chalk formation of Europe." These gentlemen first drew the attention of geologists to the true position of the beds in New Jersey, and to their probable extension to the South, where they have since been found.

+ Principles of Geology.

Traces of this ancient littoral line are usually to be found, without much difficulty, near the falls of the rivers I devoted the summer and autumn of 1833 to this demarcation, and found it to describe an irregular line west of south from Maryland into Virginia. The tertiary beds, where no fossils appear, may always be recognised by heavy, wet, dark green looking deposites, sometimes as in the hill at Richmond, on which the capitol is built, and near Shirley, on James river, containing impressions of shells only, sometimes sparkling with spienlaf sulphate of lime, and sometimes loaded with fossils, as at Fort Washington, on the Potomac. The mineral which colors these beds is a compound of silex, iron, and alkali, and is the same as that which forms an important part of the subcretaceous beds, and occasioned their being named by the European geolog sts the Green Sand Formation." The older beds may generally be looked for at the western edge of this line. Lignite occurs very commonly. I saw an important bed of it in the right bank of the Rappahannock, a few miles from Fredericksburg, on the estate of Mr. Spotswood, lying on the older tertiary. Mr. Ruffin, the intelligent editor of the Farmer's Register, who has done so much to direct the attention of his brother planters to the value of these calcareous deposites in agriculture, took me during that summer to some localities on James river, near Coggin's Point, where I found the equivalents of Mr. Lyell's Eocene period, and from which 1 enriched my cabinet with some very fine fossils. The saddle-shaped oyster appeared to be the characteristic fossil of these beds. In the interior, near Mr. Ruffin's residence, I collected a great variety of shells belonging to the present order of things, many of which, though extremely minite, retained vivid colors. It often happens that particular species are aggregated together in these localities, showing that the retreat of the ocean has been effected without breaking up their beds.

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