'Natural Tunnel', 1872. View of the Natural Tunnel, a cave that is so large it is used as a railroad tunnel, Appalachian Mountains, Scott County, Virginia, USA. 'Stock Creek, a tributary of the Clinch,...has forced or found a passage through the ridge which stretches athwart the narrow, deep valley...It is said that the projected road [the Cumberland-Gap Railroad] must pass through this tunnel, there being no other practicable route'. From "Picturesque America; or, The Land We Live In, A Delineation by Pen and Pencil of the Mountains, Rivers, Lakes...with Illustrations on Steel and Wood by Eminent American Artists" Vol. I, edited by William Cullen Bryant. [D. Appleton and Company, New York, 1872]