1886.] NEW YORK ACADEMY OF SCIENCES. 219 



lighter colored cluin usual and crypto-crystalline in structure; I 

 could find no organic remains in any of these rocks. 



The vicinity of Balcony Falls is one of the most interesting 

 localities that it has ever been my privilege to visit. It is di- 

 agonally across the valley from the Natural Bridge, on the R. & 

 A. R. R. Here the James River effects its passage through the 

 western quartzite foot hills of the Blue Ridge in a deep, narrow 

 valley. The building of the canal and subsequent construction 

 of the railroad on its tow-path have afforded excellent rock ex- 

 posures. The most northwestern cut is through white, vitreous, 

 thick bedded quartzite, dipping 60° N. W., with strike N. 53° 

 E. This contains unmistakable borings of Scolithns, undistin- 

 guishable from the ^S*. linearis, of the New York Potsdam. 

 Following the R. & A. R. R. eastward from these exposures, this 

 vitreous quartzite extends about 500 feet, its dip becoming less 

 steep, and is succeeded conformably by some 800 feet of soft, 

 argillaceous, thinly bedded, beautifully laminated and variegated 

 sandstones, much contorted, but at their contact with the quartz- 

 ite dipping 30° N. W., and so underlying the latter. These 

 tender sandstones contain flakes of white mica. They extend to 

 Balcony Falls station, and are there followed by glassy quartzite 

 again, dipping 50° N. W. The relations of the two at this 

 point I could not satisfactorily determine. Proceeding farther 

 east along the track there again succeeds a thinly bedded, beau- 

 tifully contorted sandrock series, very greatly resembling the one 

 above described. This has, in general, a very gentle northwest- 

 wardly inclination, varying to horizontal, and with local dips in 

 the opposite direction indicating several gentle undulations in 

 the strata. This series is exposed along the line for about 1,000 

 feet and then succeeded by vitreous quartzite again, which is in the 

 form of an anticlinal and synclinal fold, followed to the east by 

 argillaceous sandstones, again dipping 15° N. W., and so pass- 

 ing under the quartzite. High up in the steep bank the glassy, 

 thick-bedded rock is again seen, occupying its superior position 

 as regards the softer rocks, and dipping about 10° N. W., vary- 

 ing to horizontal, and exposed for about 600 feet. This appears 

 as a detached sheet of rock. Farther east we find it at the level 

 of the track, dipping 65° N. W., and extending thus for about 

 1,000 feet where there again succeeds a softer, gray, slaty sand- 

 rock, the junction being marked by an overhanging ledge of 

 •quartzite, with some quartz pebbles; the two series are here, as 

 elsewhere observed, quite conformable, dipping 35° N. W., 

 strike N. 55° E. Much of the softer rock is beautifully banded 

 and variegated. 1 have little doubt that the glassy quartzite 

 was once a continuous sheet of rock overlying the softer sand- 

 stones; this has been broken along at least three lines in the 



