DIVISIONS. The Appalachian region has not a uniform conformation throughout its extent, but is divided into two sections, the Northern and the Southern Appalachians, with the line of separation in western Virginia. This division is not merely of an arbitrary nature, but is founded on well-marked differences in the structural and physiographic features of the two regions. In the northern division the Blue Ridge range has gentle slopes, rising usually to rounded crests, which show a gently undulating sky line, with here and there a peak rising a little higher than the usual level. (See BLUE RIDGE.) To the west of this ridge' is a more or less elevated northerly extension of the great Appalachian Valley, which in general presents a succession of depressions and heights, the former worn by streams to a depth, in some cases, of 20U feet, while the latter rise to a height of usually less than 1000 feet above the depressions. The Alle ghany Mountains rise west of the valley in bolder sculpturing than that of the Blue Ridge, the side toward the great interior valley, the "Alleghany front," being steep and rugged; but on the side of the Mississippi Valley the slope is gradual, descending westward in lessening ridges from the plateau which marks the summit region; this configuration is due to the fact that the stratified rocks (see below) incline westward, exhibiting their upturned edges in precipices toward the east. Beginning with the Catskills. the line is broken by the broad valley of the Delaware. hut reappears in several promi nent ranges in Pennsylvania. The westernmost, or 'front' range, is confusingly called First, or Blue Mountain, with Peter's, or Second Moun tain, behind it, east of the Susquehanna. East of the Susquehanna, the Tuscarora, Blacklog, Jack's, Standing Stone, and Tussey's are well-defined ranges westward, filling the whole region with crowded heights to the long range distinctively termed Alleghany, which stretches from the border of New York down into West Virginia. In the Virginias both the Blue Ridge and the western ranges become loftier and better de fined. The front range is here called the Great North Mountain, and west of it lie successively the Shenandoah and several broken ranges. ris ing to the continuation of the Alleghanies prop er. These draw together at the southwest ex tremity of Virginia. where a new uplift, the Cumberland Mountains (q.v.), rises west of them, and terminates in the Clinch Mountains. The valley of the Tennessee makes a break, south of which the range reappears in the prolonga tions of the Cumberland Mountains in northern Alabama. In New Jersey the 'Highlands' of the
Blue Ridge rise to heights of 1000 to 1500 feet; in Pennsylvania to 2000 feet; in Virginia from 2000 to 4000 feet (Hawk's Bill. 4066 feet.), and with a breadth of 16 miles. In North Carolina, near the Virginia line, the Blue Ridge forks, the Unaka Mountains, of somewhat greater altitude, but of lesser continuity, branching off toward the southwest, while the Blue Ridge proper takes a more southerly course. The Alleghanies, which really begin with the Catskills, in New York State (highest 4200 feet), have in the northern part a general elevation of about 2000 feet, which increases to 4400 feet in Virginia and Kentucky, and still farther south decreases from 200 to 2500 feet. The absence of any isolated peaks is highly characteristic of the whole Alleghanian region; the mountains everywhere present the appearance of long, evenly topped ridges, and the name applies to the whole ridge.
The prominence of the Blue Ridge is the characteristic feature of the southern division of the Appalachians. This rises suddenly from the Piedmont tableland, east and south of it, to heights far greater than the Alleghanies at tain. Beginning prominently in South \loun tain, in southern Pennsylvania, it stretches southwestward in greater and greater heights, through Virginia and western North Carolina, where it divides, the northern branch continuing westward to Georgia as the Unaka, or Great Smoky \lonntains. These form a broad mass of mountains on the border between North Caro lina and Tennessee, containing peaks exceeding those of the White \lountains of New Ilamp shire, and consequently the highest east of the Pocky Nountalns. The culminating group, reaching in 3lount \litchell 67 10 feet, is known as the Black Mountains (q.v.), and contains many peaks above 6000 feet in height. The l'naka \fountains are characterized by the great sharp-ridged spurs which leave the main chain and preserve its-height for a distance of several miles; between these spurs are deep valleys only wide enough at the bottom for the creek-beels which are invariably found there. The altitudes of the extended valleys in this great highland region are from 2000 to 3000 feet. To the west of the steep-sided Unaka ridge lies a valley, ahout 50 or f0 miles wide, in Tennessee, which contains the Tennessee River and its tributaries, the Clinch, Holston, and French Broad.