VOLCANIC ACTION IN NORTH CAROLINA. LECTURE DELIVERED BEFORE THE WASHINGTON By Hon. T. L. CLINGMAN. More than thirty years ago my attention was directed to statements that a certain mountain in the northern part of Haywood County, North Carolina, was, at intervals of two or three years, agitated and broken into fragments along a portion of its surface. In the latter part of the year 1848, I visited the region, and soon afterwards wrote a description of the mountain, which was first published in the National Intelligencer, of the date of November 15th, 1848. As the article occupies two or three columns of the paper, giving a minute description of the locality, its minerals, and the appearance as presented at that time, with suggestions as to the probable cause of the phenomena, I will not detain you with its reproduction. The material facts may be briefly stated as follows: Between the Blue Ridge, which in North Carolina separates the waters falling into the Atlantic, from those discharged into the Mississippi, and the great chain on the Tennessee border, designated in its course by such names as Iron, Unaka and Smoky, there is an elevated plateau of more than two hundred miles in length, with an average breadth of fifty miles. The beds of the larger streams are two thousand feet above the sea, and the general level of the country, exclusive of the mountain ranges, may be estimated at twenty-five hundred feet above tide-water. Geologically considered, it is next to the Lake Superior region, regarded as among the oldest on the surface of the globe. Granite in its varieties is seen in many places, but the predominating surface rocks are of the older metamorphic strata, gneiss, and mica slate are the most prevalent, though hornblendic and magnesian rocks are abundant, with occasionally large veins of quartz, and indeed such a variety of minerals as perhaps no other region of equal extent produces. Haywood county joins the State of Tennesse on its northern border, and the seat of the disturbance is within less than twenty miles of the line of that State. A considerable range of mountains extends north and south along the line which separates the counties of Buncombe and Haywood. From the west side of this extends a ridge which terminates near the head of Fines creek. A quarter of a mile from its western end, as one moves up it towards the east, is the locality referred to. The effect of the disturbance is visible near the crest of the ridge and extends in a direction nearly due south, down the side of the little mountain, four or five hundred yards, to the level ground, and across it for some distance and along the elevations beyond. The whole extent may be a mile in length, with a breadth of not more than a couple of hundred yards at any point. The top of the ridge, where evidences of violence. are seen, is perhaps three or four hundred feet higher than the ground below. There are cracks in the solid granite of which the ridge appears to be composed, but the chief evidences of violence were ob servable a little south of the crest. From thence along the side of the mountain as one descends, there were chasms, none of them above four feet in width, generally extending north and south, but also occasionally seen in all directions. All the large trees had been thrown down. There were a number of little hillocks, the largest eight or ten feet high and fifty or sixty feet in diameter. They were usually surrounded by what appeared to have been a narrow crevice. On their sides the saplings grew perpendicularly to the surface of the ground, but obliquely to the horizon, making it manifest that they had attained some size before the hillocks had been elevated. I observed a large poplar or tulip tree, which had been split through its centre, so as to leave one-half of it standing thirty or forty feet high. The crack or opening under it, was not an inch wide, but could be traced for a hundred yards, making it evident that there had been an opening of sufficient width to split the tree, and that then the sides of the chasm had returned to their original position without having slipped so as to prevent the contact of the broken roots. As indicating the sudden violence with which the force acted, a large mass of detached granite afforded a striking illustration. From its size I estimated that it might have weighed two thousands tons. It seemed from its shape to have originally been broken out of the side of the mountain above, and to have rolled in mass a hundred yards downward. It lay directly across one of the chasms two or three feet in width, and had been broken into three large fragments, which, however, were not separated a foot from each other. The irregularities of the lines of fracture were conformable, and rendered it certain that the mass had been broken by an instantaneous shock of great violence, which did not continue to act long enough to remove the fragments to a distance In like manner a blast of gunpowder often breaks a rock into fragments, without removing the pieces out of their places, the narrow fissures caused by the explosion, permitting the gasses to escape easily. All persons who saw this locality immediately after shocks spoke of the fact that every stone or fragment of wood had been lifted out of its former bed. When I was there I was told that three years had elapsed since the last previous shock. They were first noticed about the year 1812, and usually repeated at intervals of two or three years. In 1851, I visited the locality again, having been informed that a feeble jar had occurred. As soon as I arrived at the locality, I was struck with the truthfulness of what many persons had told me, that after each shock the appearance of the place was so much changed that it did not at all resemble itself. On this occasion, though the shock had been a feeble one, I found the appearances very different. The greatest evidences of violence were near the foot of the ridge, the branch having been somewhat turned out of its course: Near this place a rock, of considerable size, had been thrown up and had only partially settled back, owing to the closing of the opening under it, so that the former earth marks were seen several feet above the ground on its sides. In the year 1867, I saw the locality again. A number of shocks had in the meantime occurred, and the appearances were very different from what they had been. From the top of the ridge to the base it seemed a mass of rocks, most of the earth having been carried away. The depression at the top was greater, while the successive jars had, under the action of the force of gravity, moved the mass downwards, and had forced she stream still further away froin the hill The violence had at one point extended itself a little further to the east. A large oak tree of great age and four or five feet in diameter, had been entirely split open from root to top, and thrown down so that the two halves lay several feet apart. As already intimated, the mineral substances resemble those of this region of country generally. The top of the ridge appears to be a mass of granite, in which the feldspar predominates, with occasionally segregated veins of quartz of small size. Some of the quartz contained thin seams of specular iron, and there are within three or four miles, two deposits of magnetic iron. Some hornblende was visible about the spot. I know of no volcanic rocks in hundreds of miles of this locality. The only sedimentary rocks are the conglomerates, and secondary limestone in the vicinity of the Warm Springs, fifteen miles distant, near the French Broad river, in a basin or gorge fifteen hundred feet lower than this locality. The extent and configuration of the ground acted on, the long intervals between the shocks, for a period of nearly a century past, and of the absence of heat and of the continuous escape of gasses, rendered it evident that these disturbances were not due to such a merely local cause, as the combustion at a short distance below the surface of a bed of inflammable mineral substances. Though in the opinion of Mr. Fox and others, there are electric currents in certain mineral veins, yet no observations heretofore made would justify us in attributing such phenomena to electricity. It seemed more plausible to adopt the view that these shocks were due to a low manifestation of volcanic action. If a long narrow chasm had been produced by some former earthquake, which extended to the heated mass below, this chasm might be filled with heated gases, which did not readily find a vent for escape, until they increased in quantity and tension so as to break through the strata immediately above them. Coming upward they might give the rocks nearer the surface a violent jar, which would continue but for a moment, and cease because the gasses escaped through the various fissures created. Such things might possibly occur at long intervals, after the manner in which Sir Charles Lyell accounts for the Geysers, or intermittent hot springs. It has been often said that volcanic action is limited to areas near the sea. Though such is generally true, yet Humboldt had no doubt but that there is in Asia, an active volcano more than thirteen hundred miles east of the Caspian Sea, and still further distant from both the northern and southern oceans. Comparatively recent lavas are found in the Rocky Mountains, six hundred miles from the ocean. In my former publication, it was suggested that if the phenomena at this point were due to volcanic action, similar disturbances would be noticed at other localities in the Alleghany range. I was soon informed that three or four years previously in the south-eastern part of Macon county, between the Tuckasegee river and the Cowee Mountain, the ground was shaken violently for several minutes. A few days afterwards some persons discovered a fresh chasm. two or three feet wide, which extended more than a mile. This was in the month of June, and they said that the leaves and branches of timber immediately above the chasm, in places, presented the appearance of having been scorched. Though I was not able to visit the place, yet from the character of my informants, I do not doubt but that the facts were as above stated. I have also been informed that in the county of Cherokee, in the year 1829, or thereabouts, the Valley River Mountain was cleft open for a considerable distance, during a violent shaking of the earth in that vicinity. The chasm though partially filled up is represented as still visible. Mr. Silas McDowell, of Macon county, a highly respectable and intelligent gentleman, accustomed to observe and write on such subjects, has stated recently in a paper published in Asheville, that many years since, there was a violent shock in the neighborhood where he resides, during which a chasm was opened on the north side of the mountain which separates the Ellejay waters from those of the Sugar Fork river. He states that the opening is still visible. This locality is eight or ten miles to the south-east of Franklin, in Macon county. About three years since I heard from many persons, that for several weeks smoke continued to issue from a small crevice in the rock, in Madison county. Not long afterwards I went to the place, and though the smoke had previously ceased to issue, yet there was evidence that the locality had at some time, probably during the present century, been subjected to violence that had changed the outlines of the ground and surface rocks. This spot is about fifteen miles east of the Haywood Mountain, and about as far from the Warm Springs to the northwest of it. Lastly, we have to notice the disutrbance of the Bald and Stone mountains. They are situated six or eight miles to the east of the Blue Ridge. Between the head waters of the Catawba and those of the Broad river, there extends for many miles eastward a range of mountains attaining the height, in places, of four thousand feet. The Bald and Stone mountains, from their appearance, are probably the highest part of this ridge, and nearly equidistant from the Catawba and Broad rivers. My information with reference to them is derived entirely from conversations with a number of gentlemen, and from the accounts published in the newspapers. The first shocks were perceived on the 10th of February last, and they were for the first month or two more frequent than they have since been. During the last two months they have occurred at intervals of a week or two, but have been rather more violent than the average. Within the last five months probably a hundred shocks, accompanied with noises, have occurred. The distance from this point to the Valley River Mountain, in Cherokee, nearly due west, is more than one hundred miles in a direct line. From the mountain in Haywood, to reach the parallel of latitude passing through the mountain near Ellejay, in Macon, one must travel more than thirty miles south. It is thus manifested that there is a belt of country more than a hundred miles in extent, from east to west, by thirty in breadth, in which such disturbances are observed. In the present state of scientific knowledge, it may not be an easy task to offer an explanation of the causes which will be generally accepted as satisfactory. Sir Charles Lyell has with great ingenuity and an array of plausible arguments, advanced the opinion that the changes which the earth's surface has undergone, have been produced by causes which are now acting to as great an extent as they have ever done in the past. To use his own striking language, instead of representing nature as "prodigal of violence and parsimonious of time" he would reverse the proposition. Without our adopting this theory, which does not seem tenable, it is nevertheless evident that the earth is far from being in a state of rest, and that its surface, judging from the observations heretofore made, appears to be undergoing changes, doubtless due to its internal condition. While a portion of Greenland, six hundred miles in length, from north to south, and of the coast of Italy near the temple of Jupiter Serapis, are slowly sinking below the waters of the sea, in the northwest of Europe from the North Cape to Sweden, a distance of a thousand miles, the land is rising at the rate of a few feet in a century. Again, while an area of one hundred thousand square miles in Chili, has been permanently raised as much as three feet by the shock of a single earthquake, a large tract of two thousand square miles in extent, in Hindoostan, has been sunk with the houses on it below the waters of the Indian Ocean. Between those two classes of violence, which represent the extremes of slow and sudden action, there may be many degrees of force greater or less. Is it at all improbable that owing to some condition of the interior of the earth, there may be a change in progress in this portion of the Alleghanies, more rapid than those observed in Greenland or the north of Europe, and yet falling short of such violence as great earthquakes and volcanoes have developed? If this portion of North Carolina were sinking into the molten mass below, solid strata might be brought in contact with matter so hot as to be decomposed in part, with the evolution of gaseous matter. If, on the other hand, there were an upheaval in progress, of this region, which seems to be the more probable assumption, then the pressure from below might occasionally cause cracks or fissures in the solid strata near the surface. Into such fissures of course the melted matter would be injected and by its great heat fuse some of the solid strata, and partially decompose them. In this manner not only would their water of crystalization, and such streams as it might come in contact with, be converted into steam, but hydrogen, carbonic acid, sulphurous compounds and other gaseous substances, would be liberated in great volume. Filling as they do, the upper portion of the fissures, as their volume and tension from heat increased, they would produce other frac tures and explosions, until they finally escaped through openings near the surface. If, from any cause these openings should be closed, then |
