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[Assembly 
five feet thick, of a coarse and highly siliceous texture. At this place, 
its surface is sixty feet below the grayband: the rocks above and below 
it are the red marl. This stratum evidently thins out in an easterly di- 
rection, as it is not seen east of Medina. 
Mr* Conrad, (Geol. Report,- 1837,) mentions the occurrence of the 
fresh water and marine shells just noticed, at Medina, and supposes them 
to have been transported from their fresh water habitations by a gentle 
current running into the ocean. I am gratified in being able to add ano- 
ther fact, in proof of the existence of a current, during the time this 
distinct stratum, or bed of sandstone was deposited. Near Lockport, 
this stone is quarried for flagging stones; it divides into layers of from 
half an inch to four inches thick. The Lingula are discovered at this 
quarry, on the surface of different layers, from two to five feet below 
the top of the stratum. As the layers are removed, these Lingula pre- 
sent a singular appearance, having their mouths all arranged in the same 
direction, and appear to be disposed, at regular intervals, over a great 
extent of surface. The direction of the mouth is to the S. E. by S. 
and the beaks in the opposite direction, or N. W. by N. There is a 
little ridge of stone extending from the beak, and gradually sloping down 
to the regular surface of the rock, like a deposit of sand, before some 
obstacle in a current. On each side of the mouth, or widest part of the 
shell, there is a depression, evidently produced by the current-, and cor- 
responding precisely with what we observe where a current of water 
meets an obstacle, as it would in this case, in the Lingula attached to 
the sandy bottom. Their mouths were, doubtless, in the direction from 
which the current came, for the purpose of obtaining food. It is im- 
possible to avoid the conclusion, that the surface of each of these layers 
was once the original surface of the sandy bottom of an ocean, covered 
with living shells, over which a gentle current flowed. There appears 
to have been a considerable interval between the deposition of one stra- 
tum and the next, for we find several successive layers with the Lingu- 
la arranged in this manner; and I have never seen them imbedded in 
the rock, or in any other position than the one described. 
The direction of the current is pointed out by the ridges extending 
from the beaks of the shells, and we thus have evidence of its course in 
the sea, from which this rock was deposited, as well, and as certain as of 
the diluvial current from the scratches on the surface rocks, or of a recent 
current from its action on a soft and yielding bed of sand or clay. Be- 
sides the fossils already noticed, we find in the upper part of the forma- 
tion the Dictuolites Beckii, and Fucoides Harlani. 
