stone
and limestone, in stratifications nearly horizontal, with occasional
beds of clay slate. A mixture of the two former frequently occurs among
the alternations presented by these rocks. A variety of rock resembling
the French burr occurs in abundance on Butcher's-fork of Powell's river,
about twenty miles northwardly of the Natural Tunnel. Fossils are more
or less abundant, in these and other rocks. Fossil bones, of an
interesting character, have been found in several places. Saltpetre
caves are numerous. Coves, sinks, and subterranean caverns, are
strikingly characteristic, not only of the country circumjacent to the
Natural Tunnel, but of the region generally situated between the
Cumberland mountain, and the Blue ridge or Apalachian mountain.
Bituminous coal, with its usual accompaniments, abounds in the northerly
parts of this region; and in the intermediate and southerly portions,
iron, variously combined, often magnetic, together with talcose rocks,
&c. &c. are to be met with in great abundance.

"The mountains in this vicinity--long. 82 deg. to 84 deg. W. from Greenwich,
lat. 35 deg. to 36 deg. N.--are among the most lofty of the Allegheny range.
Several knobs[3] in this part of the range, among which may be
enumerated the Roan, the Unaka, the Bald, the Black, and Powell's
mountains, rise to the height of at least four thousand five hundred
feet above tide."

Mr. Featherstonhaugh remarks, that the Natural Tunnel has not been
worn through the rock by the long-continued action of running water is
evident, not from the cavernous structure alone of the general country,
but from the form of Powell's mountain, in a spur of which the Tunnel
passes transversely.

Mr. Featherstonhaugh further concludes the Tunnel to be a natural cavity
in the rock, for, if such had not been the case, "it is evident that the
stream would have been deflected from its line; would have followed the
base of the hill, and have turned the extreme point."

Little is known of the geology of the country in which this Tunnel is
situate, notwithstanding the popularity of the natural bridges of the
State. The rock before us would appear to belong to that class which
geologists commonly term Perforated Mountains, which some suppose
to have been bored through, in part, at least, by the persevering
industry of man. "Such phenomena," observes Maltebrun, "are, however,
mere eccentricities of nature, and differ from caverns only from
the circumstanc