These "faults,1' however, are met with in several of the states, but particularly in S. W. Virginia, where they extend for about 100 m. in length, their course being the same as that of the anticlinal axes out of which they grow. They appear to have resulted from the lateral thrust toward the northwest of the folded piles of strata. They are observed, always beginning on the N. W. side of the anticlinal axes, in tracing these along their course, the strata on this side becoming steeper and steeper, till at last they are inverted, and dip toward the southeast. At this point the strata appear to have burst asunder along the line of greatest curvature, and the S. E. portion to have been lifted up, bringing its lower strata against the higher members on the other side of the line of fracture. The depth of this dislocation, or the extent of the displacement, increases toward the centre of the line of fault; and where the length of this line, as in the district under consideration, stretches along for 100 m. or more, it cannot appear disproportional that the vertical displacement should in its central portions amount to 1/20 of this distance; and that the lower groups of the Appalachian system, usually separated by intervening strata of four or five miles in thickness, should be brought in contact, so that the edges of one series abut against the edges of the other.

Thus the lower limestones of the great valley of Virginia are seen in Montgomery county, and thence westward along the line of the Virginia and Tennessee-railroad, in vertical position, with the strata of the far more elevated series containing coal beds dipping toward them, as if the more recent formations passed beneath these ancient groups. The thermal springs, which are of frequent occurrence along the Appalachian chain, and particularly so in Virginia, flow out almost universally on the lines of anticlinal axes, or of the faults. Their elevated temperature indicates the great depths from which they rise, and consequently that to which the folds and fractures of the stratification reach. - The geological formations of the Appalachian belt, comprising all the groups from the granite to the coal, are abundantly productive in the most important ores and minerals, which especially belong to these different formations. In the ancient granitic rocks which skirt the edge of the lower stratified formations, and sometimes spread out over broad areas, as in the mountainous region W. of Lake Champlain, in the highlands of New York and New Jersey, are found inexhaustible repositories of magnetic iron ores, which already are worked to great extent in connection with the valuable beds of hematite ores that are found conveniently near them, ranging from Canada to Alabama along the line of the great Appalachian valley.

These beds occur in great depressions in the lower limestones and metamorphic slates of this range, and sometimes in veins in the same rocks, and are worked in every one of the states through which this passes, everywhere presenting the same peculiar features. They arc frequently of extraordinary extent, and though worked in several instances for more than 100 years, the actual depth to which they reach, and their real nature, have never been fully explored. Together with the magnetic ores, they furnish the supplies for a very large proportion of all the iron manufactured in the United States; and the numerous bodies of them still untouched are a provision for still larger demands for generations to come. The value of these repositories can hardly be overestimated, particularly when considered in connection with the long extent of their range, not far back from the coast, and the enormous supplies of mineral coal that can be conveniently brought to effect their reduction. Far more valuable are they than the gold found in the granitic and metamorphic rocks of the eastern ranges, though this, judging from the production of certain localities in the southern states, would, if exposed by the great irregularities of the surface, like those of California, be found as rich and abundant as there.

It is worked in alluvial deposits enriched from the auriferous veins; and these also contain ores of copper and lead, and occasionally of silver. These deposits and veins are met with in the valley of the Chaudiere below Quebec, and are again seen in a few localities in Vermont; but their great development is on the eastern borders of the Appalachians S. of the Potomac. The copper ores met with in the rocks of the Appalachian system have never proved of great importance. They are found along the range of the talcose and micaceous slates of the Blue Ridge, as well as associated with the gold further toward the southeast. In Virginia these slates produce some workable beds of lead ore, and display occasionally attractive appearances of copper. In New Jersey the same range produces the remarkable red oxides of zinc associated with Franklinite, which are worked together, the one to produce the white zinc paint, and the other a superior quality of iron for the manufacture of steel. Further S. along the same belt are found, in the Lehigh valley and in Lancaster county, Pa., the valuable silicates and carbonates of zinc, called calamine, which are worked for the same purpose as the red oxides of New Jersey. Veins of lead ore are found m several of the formations; and in Wythe county in S. W. Virginia a mine in the great limestone formation has been worked with some interruptions for more than 100 years.

These lead veins, however, of the lower members of the Appalachian system, have for the most part proved of little importance; indeed, throughout the range of the mountains none of the formations above the metamorphic rocks are rich in any other metallic ores than the hematites which are occasionally met with, the red fossiliferous iron ores of Formation No. V. of the Pennsylvanian survey, called in New York the Clinton group, and the argillaceous ores of the coal measures. No rock formation is more useful to man for the variety and value of its productions than the true coal formation. It furnishes the great supplies of anthracite and bituminous coal, beds of fire clay, and west of the Alleghany ridge abundant beds of limestone. Salt water is obtained by boring artesian wells to lower members of the series, and the brine flows up or is pumped up into the valleys, to be evaporated by the combustion of the coal found in the neighboring hills. In many localities, where the salt-bearing rocks approach the surface, the brine is more readily obtained in large quantities, and the coal is transported for its evaporation. The formations that furnish the salt also contain great beds of gypsum.

Onondaga county in New York is famous for these productions, and in Washington county in S. W. Virginia solid beds of salt are struck in the midst of the most extensive plaster deposits. - From one extremity of their range to the other, the Alleghanies have furnished large supplies of the valuable white pine; and many of the less accessible districts of the belt still abound with it. Far toward the north, upon the better soils of the mountains, the hard-wocd forests prevail - the fine sugar maple, of the curly and bird's-eye varieties, and the white birch. The ash and the beech also attain their highest state of perfection in the most fertile soil of these northern mountains. Upon the poorer lands, and along the ravines of the mountains, the "black growth " flourishes - the evergreens, as the different species of the pine family, the spruce, the hemlock, cedar, and balsam fir; and in the swamps, the hackmatack or larch. The varieties of the oak appear further S. upon the range, these and the chestnut taking the place of the maple, birch, and beech, and, to some extent, of the evergreens also. The large cherry tree, so valuable for its timber, is met with in Pennsylvania, scattered upon the mountains; in W. and S. W. Virginia it forms forests of itself.

The white oak, the white poplar, the white and yellow pines, and the chestnut are the valuable forest trees of the mountains of Virginia. In some localities still further south, the dark growth of the coniferae covers the summits, as found, for instance, by Prof. Guyot in the group in North Carolina named the Black mountains from the dark foliage of its balsam firs, spruce, and hemlock. Among the flowering shrubs, none are more beautiful than the varieties of kalmia, azalea, and rhododendron, which are found in the greatest profusion upon the slopes of the Alleghanies and along their watercourses, giving to the rough places of the mountains the rich colors of cultivated gardens.