This section is from "The American Cyclopaedia", by George Ripley And Charles A. Dana. Also available from Amazon: The New American Cyclopędia. 16 volumes complete..
Toward the north and the south from this central portion, the plateau becomes more elevated, as well as the summits that rise up from it. In North Carolina, near the borders of Tennessee, and in the northern part of Buncombe county, the base of the Black mountains, which have been an especial subject of examination by Prof. Guyot, is found to extend from 100 to 150 m. in length, with an elevation of 2,000 ft. Above this many summits are found reaching more than 4,500 ft. higher, as the Black Dome, the height of which above the sea is 6,760 ft.; the Balsam Cone, 6,068; the Black Brother, 6,671; Cat-tail peak, 6,595; Hairy Bear, 6,597, etc. The great elevation of this group makes it the culminating point of the system. Mt. Washington in New Hampshire, though found by the measurement of Prof. Guyot to be but 6,288 ft, above the sea, which measurement differs only three feet from that made by the officers of the coast survey, appears much more elevated than the summits of the Black mountains, from its rising from a plateau of not half the height of the base of this group. - In the southern part of Pennsylvania other parallel ridges succeed to the Alleghany mountains: Negro mountain, Laurel lull, and Chestnut ridge, each a repetition of the other, at distances about 10 m. apart, and each occupying nearly as great a breadth as the valleys which separate them.
The capping of their summits is the conglomerate rocks, which underlie the coal measures. These strata arch over the crests of the ridges, projecting in bold cliffs, and on each slope dipping beneath the coal measures, which in the valley hills attain their greatest thickness. Thus the same strata appear upon the summits, and in undulating lines pass beneath the valleys to reappear upon the crest of the next ridge, and so on till, dipping down the western slope of Chestnut ridge, the coal measures spread in nearly horizontal strata over the western portion of Pennsylvania, Maryland, and Virginia. Their lowermost layers reappear as they rise to the surface upon the other margin of the great coal basin, as far into Ohio as Zanesville, and thence along a line extending to the mouth of the Scioto. In the gentleness of the dips of the strata, this western slope presents a striking contrast to the highly disturbed stratification of the Atlantic slope. There the rock formations, nearer the disturbing causes which have elevated the mountains and metamorphosed the rocks of the most eastern ridges, are thrown into confused and intricate positions, and pressed into folds and wrinkles, the prevailing inclination of which is toward the southeast - as horizontal layers of heavy cloth, pressed laterally by irresistible force from one end of the pile, would be lifted into folds, whose general inclination, by the falling back of the arches, would be toward the direction where the force is applied.
The direction of the line of force is that of the ridges themselves, or rather of the anticlinal and synclinal axes, the one being the crest of wave-like form into which the strata are thrown, and the other the trough. This, too, is the line of the great fissures, which, now filled with'metallic ores, constitute the mineral veins of the chain. It is the line of the rents caused by the earthquakes of the present period; and it is regarded by the Profs. Rogers as the line along which the elevating force that lifted the mountains extended, moving onward at right angles to this line, with a wave-like motion, till the result was attained of placing the ridges in their present positions. Toward the southeast, whence the movement proceeded, the axes are crowded near together. Toward the northwest they are repeated at distances gradually increasing, till the undulations at last flatten out and die away in the horizontally stratified regions of the west. The straightness or regular curvature of these axes, and their parallelism in distinct groups, continued for distances sometimes amounting to over 100 m., without change in the stratification or topography, cannot fail to excite the astonishment of the geological observer.
Among these axes are particularly noticed by the Profs. Rogers the straight axis of Montour's ridge in the Susquehanna region, which extends about 80 m.; the beautifully inflected axis of Jack's mountain, in the Potomac region, 90 m. long; and that of the Knob-ly mountain, nearly a continuation of the last named, itself 100 m. long. In S. W. Virginia, the straight axis of Clinch mountain is traced for more than 120 m. - The strata of the Appalachian system are all of marine or terrestrial origin. The fossils they contain are all of families belonging to the salt water, or plants of terrestrial growth. The latest or uppermost groups are those of the coal formation. Throughout the whole chain none of the stratified rocks belong to a later epoch. Their elevation, then, must have taken place previously to those periods, when the upper secondary rocks, that lap upon the extreme eastern border of the Appalachian formations, were deposited, and previously to those still later periods when the great deposits of tertiary marls, sandstones, and clays were produced, which cover the S. E. part of our country.
These mountains are then of much older date than the Alps or the Andes, upon the high summits of both of which rest the rocks of these later formations, containing their characteristic marine fossils. Raised probably by many successive impulses exerted on the same lines (it may be after long intervals of rest), the rush of the retreating waters appears to have opened those gaps through the ridges, which constitute a peculiar and most interesting feature in the topography and scenery of these mountains, and which could not have been produced by the action of any existing streams. The same rush of waters, acting upon piles of strata of various degrees of hardness, and consequent capacities of resistance, impressed upon these the forms appropriate to these properties. This is seen in the sharp outline of single beds of sandstone, which project from the sides of the hill, around which they outcrop; and in the receding of the profile of the mountain against the beds of softer shales and slates. It is seen on a grander scale in the peculiar forms which each of the rock formations gives to the hills or mountains it composes, and which enables one to recognize it wherever met with by a glance at the topography. - The regular arrangement of the rock formations throughout all their foldings and undulations is rarely disturbed by any of those sudden breaks which are common in other countries, and which bring into contact, by the displacement of portions of the series, strata usually far separated from each other.
 
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