DESCRIPTIONS OF THE FORMATIONS. 23 



partially greenish. It is both fine grained and coarse grained, the latter usually of the 

 deepest color, the former more variegated. The lower falls of the Genesee, below 

 Rochester, 110 feet in height, are formed by this rock. The deep gorge and 

 high cliffs on both sides of the Niagara River, at Lewiston, New York, are more 

 than one-half excavated in the Medina. 



In New Jersey it is a thick formation of red and variegated sandstones and 

 shales. Its lower beds are a dark red sandstone of a very ferruginous composition, 

 and extreme hardness, and in the middle and upper divisions of a brownish red 

 shale and a very argillaceous sandstone, partly calcareous. 



Neither the Oneida nor Medina are found west of Ohio. Some large masses of galena 

 and copper-pyrites with blende, have been found in the Oneida or Shawangunk 

 grit, on the Erie R . R. east of Port Jervis and at Ellenville, but they were soon 

 exhausted. When the Medina is a heavy coarse rock it produces a poor, barren 

 country, but in Western New York it is more calcareous, and the soil is much better. 



5 b, Clinton. This group consists of many different kinds of rocks or 

 masses, from which circumstance it was first called the Protean group. The 

 name of Clinton was given to it on account of the characteristic masses being found 

 around the village of Clinton, in Oneida County, New York. It consists of green 

 and black-blue shale, greenish, gray and red, soft marly layers, often laminated 

 calcareous sandstone, encrinal sandstone, and red f ossiliferous iron-ore beds . The 

 most persistent member of the group is the shale. It is bluish when fresh quarried, 

 but when long exposed it is always of a greenish hue. The next member is the 

 greenish sandstone, which is in thin layers, having its surface generally covered with 

 facoides. This also has a bluish tint when fresh quarried. The third persistent 

 member consists of two iron-ore beds in New York and several in Pennsylvania. 



The term Protean is still applicable to the Clinton group, which, in some 

 places, consists of thin shaly sandstones, shales, and even conglomerates ; in others, 

 of thin bedded, impure limestones, shaly sandstones, iron-ores, etc : still again it 

 appears as a duplicate series of shales, limestones and iron-ores, with some 

 intermixture of sandy matter, all containing an abundance of marine shells. In 

 the west the formation is limestone, and is of a more uniform character. 



The Clinton formation produces the celebrated f ossiliferous iron-ore, generally 

 known as the FOSSIL OEE, which occurs in it in every state from New York to 

 Alabama. In all its localities this ore is red or brownish-red, very hard, and where 

 unaltered, invariably oolitic or in larger sized concretions. In New York, where 

 it is extensively mined, there are two beds of it, generally about 20 feet apart, and 

 upon an average about a foot and more in thickness. The ooJitic particles are 

 usually more abundant in the lower, the larger sized concretions in the upper bed. 

 The two beds never appear at 'the same locality, or in the same line of section, but 

 where the lower one occurs the upper one is wanting, and where the upper one 

 occurs the lower one is not found. 



In Pennsylvania the Clinton is a very extensive formation, nearly 2,000 feet 

 thick, of slate, shales, sandstones and iron-ore, with the same variety as elsewhere, 

 and its iron ore is very rich, productive and valuable. The outcrop of the ore- 

 beds have been traced for hundreds of miles. In Dodge County, Wisconsin, near 

 Milwaukee, the Clinton iron-ore, at Iron Ridge, is from 15 to 18 feet thick, but 

 this is very unusual, and it is not in the same part of the formation as the fossil 

 ore in the east . The deposits of this ore in East Tennessee and in Alabama, 

 called the Dye-stone ore, are still more extensive. 



