444 GEOLOGY OF OHIO. 



and standing upright as it was formed, having been silted up by fine, 

 sedimentary deposits. Above this building stone the system assumes 

 that loose and porous character so often observed in this formation, full 

 of casts of large Pentamerus oblongus and other fossils, with numerous 

 small cavities stained with carbonaceous matter. At Port William the 

 exposure on Anderson's Fork was perfectly characteristic of this forma- 

 tion, the jagged and cavernous masses being worn and corroded by the 

 elements into fantastic shapes. 



But .the most interesting exposure of this formation in the county is 

 that known as Black's quarry, near Snow Hill, where the strata belong 

 to the upper portion of the Niagara. This is a highly fossiliferous stone, 

 but unsuitable for building purposes, as it is soft and porous and can be 

 crumbled in the hand. The stone used in constructing the Vienna and 

 Wilmington turnpike was obtained here. The fossils are difficult to ob- 

 tain without being broken, but many of them are very good specimens, 

 the most delicate markings being preserved. The stone is so fragile that 

 the specimens are greatly injured by handling, and can not be packed in 

 the usual manner without detriment. Among those I brought away I 

 find a Rhynchonella cuveata, an Athyris, a Polypora and Striaiopora, and a Fixvis- 

 tella plumosa. The molluscous fossils obtained were casts of the shells, 

 the interiors being entirely empty and showing the muscular impres- 

 sions with great distinctness. It will doubtless repay the paleontologist 

 richly to make a thorough exploration of this quarry. If there is any 

 economic value in the product of this quarry, not heretofore discovered, 

 I suggf st that it may be as material for lime. The best quality cf build- 

 ing lime is manufactured in other localities from stone obtained in this 

 horizon of the Niagara formation. There may be a question of its prac- 

 tical utility for this purpose on account of the liability of the stone to 

 break up. There were indications that in some portions of the quarry 

 the quality of the stone might be less liable to this objection. So far as 

 my observation extended, this portion of the Niagara occurs nowhere 

 else in our district. All the bedded rock eastward of the localities I 

 have named, where the Niagara may be found, belong to the same forma- 

 tion, as all places where stone in position is found along Anderson's 

 Fork, near Wilmington, and also near Reeseville. 



THE LOWER HELDE EBEEG, OR WATER-LIME. 



This formation occurs next above the Niagara, and overlifs it in 

 Fayette county. The Niagara dips to the east and the Lower Helder- 

 berg overlaps it. On Rattlesnake, in Fayette county, about one hundred 

 feet in perpendicular thickness of this stone are accessible to observa- 



