The mountains are generally, though not always, sterile, and produce nothing but forest trees; but the valleys are, with hardly an exception, rich, and productive of every variety of "grass and herb yielding seed, and fruit-tree yielding fruit." Nor are they less favoured in the mineral kingdom; possessing the greatest abundance of all the most useful and necessary minerals, of which we shall now proceed to speak in order. All the country included under the boundaries mentioned above, with the exception of some primitive ranges of mountains on the southeastern side, is apparently _transition_. This, it will be seen by a reference to Mr. Maclure's excellent map, will extend the boundary of his transition class considerably farther northwest, and make it include Cumberland Mountain and all East Tennessee. This would be evident from comparing the northwestern part of Virginia, which Mr. Maclure has included in his transition tract with all East Tennessee. Every mineralogist must observe the identity of the minerals of the two countries as well as that of their stratification and general formation. The limestone in the valleys, and the sandstone on the mountains, lie in strata which make an angle of from 25 to 45 degrees with the horizon. The limestone bears the impressions of shells, but rarely, if ever, of vegetables, and contains beds of hornstone, but not of flint, or what can properly be called flint. The rock which lies in the lowest valleys, and often rises into pretty high hills, and is seen forming bluffs on the banks of the rivers, is _limestone_: it is of a dark blue, approaching to a gray, as it is exposed to the air, and often appearing quite white. Its fracture is compact in one direction; in another it is more or less slaty in its structure. It is interspersed with veins of the crystallized carbonate of lime, more or less perfect, and of a pure but opaque white. Another variety of this limestone, not so abundant, is that which is white and red, having the white and red spots intimately mingled. Its structure is similar to the other kind. Lying in beds of this limestone, parallel to, and imbedded in, its strata, is a stone, which, from its globular form, its hardness, and its colour, has been usually mistaken for flint. On comparing it with the flint of chalk-beds, we find it much less translucent, its colour darker, and its hues duller; and its rough and irregular fracture, compared with the easy, smooth, and conchoidal cleavage of the true flint, decides it to be hornstone. It is found also forming considerable distinct beds on the hills; and is seen in detached pieces, and irregular pebbles, covering many of the ridges. Alternating with the beds of limestone, and possessing the same formation, is a soft _clay slate_. _Soapstone_ is found in it.