CLINTON GROUP. 147 



dtmispherica. It is in this second mass of green shale, that the superior bed of iron ore occurs in 

 Oneida and Madison counties. 

 5. Impure thin-bedded limestone, with thin scams of green shale, 18 feet. 



At the steamboat landing, the following series exist upon the east side of the Genesee : 



1. One hundred feet of Medina sandstone. 



2. From fifteen to twenty feet of green fragile slate. 



3. From four to six feet of sandstone. • 



4. Six iuches of the oolitic iron ore. 



5. Ten feet of sandstone alternating with shale. 



6. Eight inches of limestone containing the Pentamerus oblongus. 



Near the locks of the canal at Lockport, there is from thirty to thirty-six feet of shale, 

 and from ten to fifteen feet of limestone, containing many encrinal stems. The shale, at 

 its junction with the limestone, is a disintegrating mass. 



The thickness of the rocks at Lockport is as follows : 



1. Medina sandstone exposed 60 feet. 



2. Limestone shale and green shale, 70 .. 



3. Niagara limestone 20 .. 



The shale below the Niagara limestone, predominates greatly over the limestone or hard 

 layers, or the impure siliceous limestones. 



At this place, then, the change in the lithological characters of this series is still better 

 marked and more decided. Here the limestone and shale only remain : the coarse rough 

 sandstone and conglomerates, and the iron ore beds, are entirely absent. These, it will be 

 seen, constituted at the east the most important parts of the series. The same observation 

 applies to the series as it exists in Orleans and Niagara counties. On the Niagara river, 

 the limestone is about twenty feet thick, and the shah' has diminished to four or five feet. 

 This change in the mineral constitution of the group is both interesting and important. 

 It is important, inasmuch as the change is one which is peculiarly favorable to agriculture : 

 the hard and scarcely decomposable sandstones and conglomerates of Oneida become soft 

 decomposable slates and shales, before they reach the Genesee valley. 



General distribution of the Clinton group. I have stated somewhat in detail the pecu- 

 liarities of this group, as it appears at many places on and near the route of the Erie 

 canal. A general statement, however, of the distribution of the series is still required. 

 The first well characterized beds appear in the southeast part of Herkimer county, near 

 Vanhorn's in the town of Warren. The series forms a narrow belt, and, extending west- 

 ward, are exposed to view at the quarries of Blackstone and Davis, two and a half or three 

 miles south of Utica. The north border runs about northwest, and intersects the Erie canal 

 about half way between Rome and Oneida lake. From this region, the series extends 

 westward to Niagara, as has been intimated. The greatest width of the belt is between 

 the Oswego river and Sodus bay, or rather in the town of Wolcott, where it approaches 



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