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 geod 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 
finda Rhynchonella cuneata,an Athyris, a Polypora and Striatopora,anda Kavis- 
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 suggest that it may be as material for lime. The best quality of 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 lecalities 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 RBERG, OR WATER-LIME. 
This ‘formation ,occurs next above the Niagara, and overlies 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- 
