Page:Encyclopædia Britannica, Ninth Edition, v. 2.djvu/215

Rh APPALACHIAN MOUNTAINS 201 Guyot, from the hypsometrical explorer of the region) has CG71; Black Brother, 6619; and Mt. Hallback (Sugarloaf), 6403; besides a large number of summits varying from 3000 up to 6000 feet. In the Smoky Mountains we have Olingmann s Dome, 6660 feet high; Guyot (in Tennessee), 6636; Mt. Alexander, 6447; Mt Leconte, 6612; Mt Curtis, 6568 ; several others upwards of 6000, and a great many of more than 5000. In the whole Appalachian system, Lake Champlain is almost the only lake of any importance ; but a multitude of rivers, and some of them of considerable size, find their sources in its recesses. The watershed does not lie along any one continuous axis, but shifts its position several times along the line. In the north it is found in a stretch of country, called the Height of Land, that lies between the White and the Green Moun tains, and gives birth to the Connecticut and a number of smaller streams ; next, it is formed by the Adirondack Mountains, which supply the sources of the Hudson River; and, further south, by the high plateaus of Pennsylvania and New York, which give origin to the Delaware and the Susquehanna, with their numerous tributaries. These rivers, flowing south and east, have thus to cut their way through the successive ridges of the whole Appalachian range. The watershed is next situated in the Alleghanies proper, which send a number of affluents to the Ohio on the west, and give rise to the James River on the east; and lastly, it runs along the terminal cluster or coil composed of the Black, the Smoky, and the Unaka Mountains. Here a tributary of the Ohio, called the Red River, a number of the affluents of the Tennessee, and various less important streams, have their sources. The Appalachian Mountains are a vast storehouse of mineral wealth. Magnetite, hema tite, limonite, and other iron ores, are found in great abundance. The first is best exhibited in what is fre quently called the Champlain Iron District, where it is now largely manufactured ; and it also attains remarkable development in various parts of New York and New Jersey. The extensive deposits of this ore in Virginia, North Carolina, and Georgia, have hitherto been turned to comparatively little account. It is frequently con taminated by phosphate of lime, sulphur, and titanium. Red hematite is found in New York, Pennsylvania, Ten nessee, and Georgia, and is usually known as Clinton ore, from a place of that name in Madison County, New York, while in Tennessee it is called Dyestone ore. It is of great commercial importance, though, on account of the amount of phosphorus which it contains, it is worthless for the manufacture of steel. Limonite, or brown hema tite, which, from its fusible character, is usually worked along with the more crystalline ores, occurs in a series of beds all along the flanks of the Appalachians, from Maine in the north to Georgia in the south. The earthy carbonate of iron &quot; clay ironstone ore,&quot; &quot; shell ore,&quot; &quot; kidney ore,&quot; is found in most parts of the system in connection with the Carboniferous strata, and has been very largely manu factured. In the northern district alone that is, in the eastern part of New York, in New Jersey, and Eastern Pennsylvania the number of furnaces is about 200, and the gross production of iron 900,000 tons per annum, or one-third of the entire production of the United States. This abundance of ore would have been almost useless had it not been for the equally abundant supplies of fuel ; and the coal measures are among the most extensive in the world, the bituminous coal alone covering an area of 56,000 square miles, without counting the unrivalled beds of anthracite in Pennsylvania and New York, which cover an area of between 400 and 500 miles. While the supply of gold, silver, copper, and lead is of comparatively no importance, marble, limestone, fire-clay, gypsum, and salt are extremely abundant. Many of the ranges are richly covered with forest, and yield large quantities of valuable timber, consisting chiefly of sugar maple, white birch, beech, and ash, in the north, and oak, cherry-tree, white poplar, white and yellow pine, towards the south. The dark foliage of the pines, balsam-firs, hemlock-trees, and cedars, gives colour and name to many of the districts. Rhododendrons, kalmias, azaleas, and other flowering shrubs, often grow in almost impenetrable thickets; and in some parts the botanist is at once delighted and be wildered by the profusion and variety of the smaller plants. Bears, &quot; panthers,&quot; wild cats, and wolves haunt the forests in large numbers. The Appalachian system has a history which is of great interest, as it affords the clue to the causes of its forma tion ; but a few points only can be toiiched on here. The earliest strata in the range are of Upper Cambrian age, and during the later portion of this period the Potsdam sandstone was deposited, the nature of which demonstrates that a large portion of the United States was then a shallow sea. Upon this were superimposed strata of Silurian, Devonian, and Carboniferous age, but these deposits were by far the thickest along the broad band now occupied by the Appalachians, and where thickest they have the general character of shallow water-beds. Beds of the same age occupy the valley of the Mississippi; there they are largely composed of limestones and deep water-beds, and have an aggregate thickness of about 8000 feet, usually horizontal or only slightly inclined. In the Appalachian Mountains their aggregate thickness is 40,000 feet, and the beds are thrown into complicated folds and contortions. At the close of the Carboniferous Period the beds were deposited in shallow water, and hence there must have been a subsid ence along the band whereby the Potsdam sandstone and its associated rocks were depressed from 30,000 to 40,000 feet below the sea-level. This depression threw the strata into one gigantic synclinal basin, to conform to which the beds were necessarily crumpled up, and at the same time more or less metamorphosed. Then the beds began to rise above the sea-level, and the valleys and ridges to be formed, a process which may have been one of slow development, but which had made considerable advance prior to the Triassic age, when sandstones were deposited in the Appa lachian valleys. The elevation has continued until the Potsdam sandstone is now a few hundred feet above the sea. If the strata had retained their original character and planes of deposition relatively to the horizon, the highest mountains would have reached 40,000 feet ; but, as we have seen, they actually attain but 6707 feet. The elevation was not confined to the line of the Appalachians, but was continental in extent. During the process of elevation denudation was in operation, and by this agency the surface features of the range generally have been moulded. From this brief summary some idea may be conceived of the numerous operations and circumstances involved in the formation of a mountain chain like the Appalachians, which are intermediate in nature and in age between the older Laurentides, which are now worn down almost to a stump, and the Rocky Mountains, which have an air of comparative freshness. (For fuller details on this subject, consult the references given below and the separate articles on the States in this work: Petermann s Mittheilitngen, 1860, p. 263; Tlie American Journal of Science, vol. xxxi. p. 157, and p. 392, 1861 ; Roger s Report on the Geology of Pennsylvania, 1858; a paper by Dana in the American Journal of Science, vol. xxxvi. p. 227, 1863; Hall, Paleontology of Neiv York, vol. iii. ; Sterry Hunt s &quot;Geognosy of the Appalachian System,&quot; in his presidential address, Proceedings of American Association for the Advancement of Science, for 1872, p. 3.) II. 26