Geological Reports on the State of Neio York. 37 



hundred and seventy two feet within a mile or two. The banks 

 are vertical, presenting the most beautiful sections, and being for- 

 est clad, principally with evergreens, the scenery is in a high 

 degree grand and picturesque ; at the deepest place the perpen- 

 dicular banks are three hundred and fifty one feet high. 



Proofs of marine currents. — Near Lockport a sandstone " 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 present a singular appearance, hav- 

 ing their mouths all arranged in the same direction, and appear to be dis- 

 posed, 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 de- 

 posit 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 pro- 

 duced by the current, and corresponding 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, doubt- 

 less, in the direction from which the current came, for the purpose of ob- 

 taining food. It is impossible 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 deposi- 

 tion of one stratum and the next, for we find several successive layers 

 with the Lingula arranged in this manner ; and I have never seen them 

 imbedded in the rock, or in any 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." 



In a stratum of iron ore which appears at various places be- 

 tween Little Falls and Niagara, the ore is in some places composed 

 of fragments of encrinital columns and of corallines, with Producta 

 catenipora, &c., all of marine origin. 



Hydraulic cement. — Mr. Hall remarks that there is no rock to 

 which the term hydraulic cement is exclusively applicable ; the 

 upper strata of the gypseous formations are used for this purpose, 

 and also the silico-argillaceous portions of many limestones ; he 



