GEOLOGIC FORMATIONS OF NEW YORK 153 



Clinton Group 



Above the Medina sandstone lies a series of sandstones, lime- 

 stones and shales, which receives its name from one of the locali- 

 ties where it is well seen, the vicinity of Clinton, Oneida county. 

 This group of strata is hardly distinguishable east of Fulton 

 county, appearing to thin out in the eastern part of the state, 

 where it is all sandstone and greenish shale. In the western part 

 of the state, however, it contains two distinct layers of limestone 

 and two of greenish shale, which can be well examined above the 

 lower falls of the Genesee river near Rochester. Two thin strata 

 of iron ore are found in this group, and are extensively mined in 

 the vicinity of Clinton; the ore is of a peculiar granular appear- 

 ance like an aggregate of small shot, and contains many fossils of 



small size. 



On the Niagara river, the upper limestone of this group is about 

 20 feet thick, and a very solid, massive rock. At the falls, this 

 layer is near the level of the water below the cataract. 



This grouper rocks extends westward through Canada, but does 

 not appear beyond Wisconsin as a distinct mass. It re-appears 

 in Pennsylvania in enormously increased thickness, amounting to 

 nearly 2,000 feet, and extends southward along the Appalachian 

 chain even to eastern Tennessee. It seems everywhere to contain 

 beds of iron ore of the same character as those in New York. 



Niagara Group 



This group consists in the region from Wayne county westward 

 of two distinct members, a shale and limestone, which, are recog- 

 nized as the products of one period, during which, there was an 

 important change in the materials deposited and a lesser one in 

 the animal life. The shale is a very uniform deposit throughout 

 the whole extent of the fourth district; while the limestone, from 

 a thin, dark colored, concretionary mass at the east becomes an 

 extensive and conspicuous rock, constantly increasing in thick- 

 ness in a westerly direction, even far beyond the limits of the 

 state. 



