352 Description of a JVatural TunneL 



southerly portions; iron, variously combined, often magnetic, to- 

 gether with talcose rocks, &c. &c. are to be met with in great 

 abundance. 



The mountains in this vicinity, long. 82° to 84° W. from Green- 

 wich, lat. 35° to 36° N. are among the most lofty of the Allegheny 

 range. Several knobs* 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. 



REMARKS BY THE EDITOR. 



Our acknowledgments are due to that distinguished traveller 

 Col. Long, for having enriched our Journal with a notice of a re- 

 markable phenomenon of this continent, which no man has ex- 

 plored more extensively than himself. The natural tunnel which 

 that gentleman has so well described, is a very rare spectacle, 

 and considering its extent, unique of its kind. It belongs no doubt 

 to that class of natural aqueducts which owe their origin to 

 natural cavities in the rocks, and which are generally sub- 

 terranean. G)l. Long observes that coves, sinks, and subter- 

 ranean caverns are strikingly characteristic of the whole region 

 adjacent to the natural tunnel. This is the common character of 

 that great limestone formation (carboniferous) which extends 

 over so vast an area in North America, and which abounds in 

 extensive subterranean caverns, whether in Kentucky, Virginia, 

 or the Helderberg hills in New York. These caverns in the two 

 former states, are of a surprising extent, and have been pene- 

 trated several miles. Many coves, and curiously complicated 

 dells and vales in the south-western parts of the Apalachian 

 ridges, probably owe their origin to the disintegration of the 

 rocks, and the consequent destruction of the natural caverns. 

 That this 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, this 

 natural tunnel passes transversely. Powell's mountain is one of 

 those innumerable knobs, out-liers, or independent hills, divided 

 from the adjacent mountains by dells or vales, which are so numer- 

 ous in that vast assemblage of Apalachian mountain ridges, which 



* Outrliersof any particular ridge. 



