i6 CHARLES S. PROSSER 



This exposure is very similar to hundreds of outcrops in the 

 arenaceous Brachiopod zones of the Hamilton shales in New York, 

 and any geologist who has studied that formation in New York 

 would at once recognize the great similarity in lithologic appear- 

 ance. This, together with the presence of a Hamilton fauna, 

 apparently justifies the writer in correlating that part of the Rom- 

 ney formation shown in the highway cuts north of Romney with 

 the Hamilton formation of the standard New York section. 



Hanging Rock. — 'About four miles north of Romney is a high 

 cliff known as Hanging Rock, where the South Branch of the 

 Potomac River has cut a deep and narrow gorge from the east to 

 the west through Mill Creek Mountain. The river makes a big 

 loop, and at the highway bridge south of Springfield it turns and 

 cuts back through the ridge to its eastern side. At Hanging Rock, 

 on the northern side of the river, is a high cliff in which the anti- 

 clinal arch of the fold in the Oriskany sandstone is finely shown. 

 A fair idea of the appearance of this cliff may be gained from the 

 halftone (Fig. i .) At the western end of the gorge, by the side of 

 the highway just after crossing the railroad track, is an excellent 

 exposure of fine black to drab shales containing small concretions 

 and some fossils. In one layer at least are numerous specimens 

 of Phacops cristata Hall associated with Dalmanella, Chonetes, 

 Ambocoelia and the representatives of a few other genera. The 

 rocks are slightly arenaceous and break into small, somewhat elon- 

 gated pieces on weathering. The layer in which the fossils occur 

 abundantly is somewhat arenaceous and not very much above the 

 top of the Oriskany sandstone. The species collected in this shale 

 are given in the following Hst: 



Slropheodonta sp. 

 Chonetes cf . lepidus Hall 



[Two small imperfect internal impressions.] 

 Dalmanella lenticularis (Vanuxem) 

 Cyrtina hamiltonensis ( ?) Hall 



[Small imperfect specimen.] 

 Ambocoelia umbonata (Conrad) 

 Styliolina fissurella (Hall) 



[Abundant on some of the blocks.] 

 Phacops cristata Hall 



