Note (return) — NATURAL TUNNEL, IN VIRGINIA.

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 circumstance of having a passage entirely through them. The Pierre-Pertuise in Mount Jura, and Pausilippo, near Naples, are instances of this kind. The Torghat, in, Norway, is pierced by an opening 150 feet high, and 3,000 long. At certain seasons of the year, the sun can be seen darting its rays from one extremity to the other of this vault. Near New Zealand is a rocky arch through which the waves of the sea pass at high water."4 The latter, one of the Piercy Islands, will be found engraved and described in The Mirror, vol. xix. p. 145.