314- Geology of Lewis County. [June, 



GEOLOGY OF LEWIS COUNTY. 



BY FRANKLIN B. HOUGH, A. M. 

 [Concluded from page 272] 



The next rock in the ascending series is that limestone forma- 

 tion, which has been called by the Geologist of the Third Dis- 

 trict, the Black River Limestone," which forms a terrace, extend- 

 ing almost uninterruptedly through the county, and from a half of 

 a mile to a mile from the river. The thickness of this rock can- 

 not exceed fifty feet: and in most of the localities where it has 

 been exposed, it exhibits three distinct varieties, differing in struc- 

 ture and in color. The lower strata constitute the water-lime 

 rocks of Lowville, being at the bottom of the terrace, and having 

 a thickness of perhaps five feet. The color of this rock is a yel- 

 lowish white, with occasional masses of calcareous spar; and it 

 is, so far as observed, destitute of fossil remains. 



It has not been favorably received as a water-lime, and is not 

 now manufactured. It is said to have been examined by the en- 

 gineers engaged on the public works, who decided unfavorably 

 upon it. The bed of the creek east of Lowville village, is the 

 only locality where this rock, having the characters above de- 

 scribed, has been observed; its equivalent at other localities being 

 a reddish grey rock, with a fine grain and very compact, ringing 

 under the hauimer, and breaking with a conchoidal fracture, upon 

 receiving a slight blow. Occasionally horizontal seams occur, 

 whose weathered edges present a series of peculiar indentations. 

 like those observed in the sutures of the human skull, and more 

 rarely, portions of the rock exhibit an imperfect columnar struc- 

 ture, in connection with this. 



This structure can be observed with readiness only on surfaces 

 which have been exposed to the weather, the firmness of the rock 

 preventing it from being seen on a freshly fractured surface. When 

 the rock is broken along these sutures, each surface appears with 

 a multitude of dentiform prominences, which exactly fill the de- 

 pressions in the othei'. In some places, where this portion of the 

 rock has been exposed by the water, in wearing down a channel, 

 the characters here described appear variously modified, it being 

 in some places dark colored, or even jet black; but' throughout 

 the whole length of the county, the lower strata of the limestone 

 are destitute of any well characterized organic remains. 



Next above the fine grained and non-fossiliferous strata, occurs 

 a succession of even bedded strata of limestone, charged with the 

 characteristic fossil of the series — the Fucoides dcmissa — replaced 



