172 A. Guyot on the Appalachian Mountain System. 
the Smoky mountains and the Cumberland mountains, but 
where it has a mean elevation of not more than about 1000 feet, 
that is, only one-half of the height of the neighboring valleys 
in the mountainous region of North Carolina. 
the central portion of which, near Lexington, preserves an alti- 
tude of more than 1000 feet. 
mination of the mountains. 
