Appalachians, a great mountain-system of North America, nearly parallel with the Atlantic coast, and extending from the Gulf of St Lawrence SSW. to the west central portion of Alabama. Geologically, it is much older than the Western Cordillera, known as the Rocky Mountain system, but it is in the main much later in geologic date than the Laurentian system, which represents it on the north of the St Lawrence. It is the parent of many of the rivers of the Atlantic States; but several large streams break its continuity; and one, the river Hudson, is a tidal channel which carries even sea-going vessels through the range. The Appalachians consist, In the main, of various parallel ranges, separated by wide valleys. Even the low hill-ranges between the mountains and the sea have much of the same parallelism, and the sea-coast has in a marked degree the same general direction and curvature as the mountains themselves; while, far to the NE., the nearly detached peninsula of Nova Scotia and the island of Newfoundland are traversed by ranges exhibiting the same parallelism and the same general direction as are seen in the Appalachian ranges.

Locally, the Appalachians have various names - e.g. in the Gaspe Peninsula, the Shickshock Mountains, the Franconia Mountains of New Hampshire (where Mount Washington attains 6293 feet); the Green Mountains of Vermont are the Hoosic Range in Massachusetts; the Cat-skills and Shawangunk Mountains; in Pennsylvania and Maryland, the South Mountain or Blue Ridge, which is regarded as identical with the Unaka or Smoky Mountain Ridge of North Carolina and Tennessee; and west of the South Mountain of Pennsylvania the great Alleghany Ridge (q.v.), which often gives name to the whole system.

Nowhere do the Appalachians reach the snowline. Their highest points occur in North Carolina, where Mitchell's Peak reaches the height of 6688 feet. The principal coal-beds of this chain occur in Pennsylvania to the NNE., and in the other states southward along the mountains to their termination in Alabama, the chief coal-basins being either among the mountains, or to the westward of them. There are beds of anthracite coal on the eastern slopes of the Appalachians, chiefly in Pennsylvania, west of which the coal becomes bituminous, after we have crossed basins of semi-anthracitic and moderately bituminous coal. This coal region is one of the most productive, extensive, and important anywhere known. Of the metals, by far the most important is iron, of which various ores are largely wrought. Gold occurs chiefly to the eastward of the mountains, and is wrought at various points from Virginia to Alabama. Zinc, lead, and other metals are found in this range, which also affords marbles, slates, and a great variety of building-stones.