From where the Pennsylvania Rail Road passes the Allegheny, to where it is intended to be tra versed by the Chesapeake and Ohio Canal, is about 40 miles, the intermediate direction a very little W. of S. At the passage of the Chesapeake and Ohio Canal, the Alleghany is again elevated 2754 feet above tide level, but here also the descent each way is so rapid, that Cumberland, on the Potomac, close upon the eastern slope of the chain, is only elevated 573 feet above tide water, and on the op posite flank, where the declivity is less abrupt, the falls of Youghiogany river is only 1170 feet above tide level.
The preceding elements demonstrate the very unequal depression of the two valleys which lie on each side of the Alleghany chain. The valley westward is a real and not very lightly elevated table land, rising from 900 to 1200 feet above the oceanic level.
With that part which separates the sources of the north-western confluents of Potomac from those of Voughiogany, terminates the certain geo graphy of the Alleghany chain. As delineated on Tanner's United States, it is carried in continuity from the sources of Kiskiminitas and Juniata to New river S.S.W. and gradually inclining upon or towards Kittatinny and Blue Ridge. In the valley of Potomac, the latter and Alleghany are upwards of 70 miles asunder, whilst at the sources of Roan oke and James rivers, the two chains approach to within less than 30 miles; and as the Alleghany is drawn between the extremes along the real separat ing line of the river sources, we may from analogy doubt the correctness of the delineation. Judging from the structure of the system, it would appear that the continuation of the Alleghany chain from the sources of Potomac, James, and Monongahela rivers, is to be found in Green Briar Mountain, be tween Green Briar and Gauley rivers, and again beyond the Kenhawa in the Great Flat Top Moun tain. If this conjecture is correct, what I have long suspected will follow, that Powell's mountain, between Powell's and Clinch rivers, is a ridge of the Alleghany chain.
Where, on any map of the United States, the mountain chains are represented inflecting with the dividing line of river source, the accuracy of the mountain representation may be doubted. It is directly contrary to the character of the Appa lachian mountain ridges to inflect with the water courses, though in innumerable instances the ridges are separated by the water channels. The chan nels, as already observed, flow generally along or at right angles to the mountain valleys. But it is the circumstance of the chains, being so frequent ly traversed by the streams, which render the true delineation of the latter so difficult. The intricacy
would, however, in great part disappear, if a care ful and skilful survey was made of the whole Ap palachian system.
From the double confusion produced by nature and the want of correct maps, we may be excused from an attempt to describe, or ever, name, the nu merous chains and ridges which extend between the Kittatinny and Alleghany chains. To the in terior or westward of the latter, I have traced two lateral chains from the sources of the Monongahe la into the state of New York. Though inferior in height above their bases to the chains more east ward, the western part of the system is in a pecu liar manner distinctly defined in nature. Between the Voughiogany and the Kiskiminitas rivers, the easternmost of these western chains is called Lau rel Hill, and the westernmost designated Chesnut Ridge; but with unequalled absurdity, the names are reversed between Cheat and Youghiogany. With the Kiskiminitas valley, these two chains are omitted on some maps, and confounded on others, but really remain distinct and defined to the sources of Genessee river. A similar observation may be made on the geography of the same chains in an opposite direction. Along the comparatively great distance of two hundred miles from the valley of Cheat river to that of the West Fork of Sandy ri ver, they are again omitted, though there also dis tinct and defined.
Which of the more northern chains is continued in Cumberland Mountain, it is impracticable to determine from the representation of the maps. The Cumberland chain becomes distinct as the boundary between Virginia and Kentucky, on the higher sources of Sandy, Kentucky, Cumberland, and Powell rivers. The direction of the chain from the West Fork of Sandy river to Cumberland Gap, at the point where Virginia, Kentucky and Tennessee unite, in a distance of 85 miles, is to the west of south-west. Entering Tennessee, where, in a distance of two hundred miles, it maintains a general course of a little W. of S.W., but with a large curve to the north-west, this chain discharges from the western flank the numerous sources of Cumberland river, and from the opposite side the north-western streams of Upper Tennessee. From Tennessee it merges into Alabama, within which, about 40 miles, it reaches and is traversed by the main volume of Tennessee. Beyond Tennessee ri ver, the Cumberland chain is quickly lost amongst the hills which separates the valley of that stream from that of the Black Warrior branch of Tom bigbee.
The passage of Tennessee river through the Cumberland chain is a very remarkable point in the physical geography of the United States. See