Chesnut ridge, the last of those accessary to the Alleghany on the west, deserving the name of a mountain, is somewhat more abrupt and precipitous, than those before mentioned. This ridge is divided transversely by the bed of the Loyalhanna, a rapid, but beautiful stream, along which the turnpike is built. Few spots in the wild and mountainous regions {11} of the Alleghanies, have a more grand and majestic scenery than this chasm. The sides and summits of the two overhanging mountains, were, at the time of our journey, brown, and to appearance almost naked; the few trees which inhabit them being deciduous, while the laurels and rosebays gave the deep and narrow vallies the luxuriant verdure of spring. The Monongahela rises in Virginia, in the Laurel ridge, and running northward, receives in Pennsylvania the Yohogany, whose sources are in the Alleghany mountain, opposite those of the Potomac. This river, like most of those descending westward from the Alleghany, has falls and rapids at the points where it intersects Laurel-hill, and some of the smaller ranges. Along the fertile bottoms of the Alleghany river, we begin to discover traces of those ancient works so common in the lower parts of the Mississippi valley, the only remaining vestiges of a people once numerous and powerful, of whom time has destroyed every other record. These colossal monuments, whatever may have been the design of their erection, have long since outlived the memory of those who raised them, and will remain for ages affecting witnesses of the instability of national, as well as individual greatness; and of the futility of those efforts, by which man endeavours to attach his name and his memorial to the most permanent and indestructible forms of inorganic matter. In the deep vallies west of the Alleghany, and even west of the Laurel ridge, the metalliferous limestone, which appears to be the substratum of this whole group of mountains, is again laid bare. In this part of the range, we have not observed those frequent alternations of clay-slate with this limestone, which have been noticed by Mr. Eaton and others in New England.[006] In its inclination, and in most particulars {12} of external character, it is remarkably similar to the mountain limestone of Vermont, and the western counties of Massachusetts. Many portions of the interior of the state of Pennsylvania have a basis of this limestone. When not overlaid by clay-slate, and particularly when not in connexion with sandstone, the soils resting on the transition limestone are found peculiarly fertile and valuable, having usually a favourable disposition of surface for agricultural purposes, and abounding with excellent water.