LIME AND CEMENT INDUSTRIES 761 



Schoharie not over 240 feet. Westward from Schoharie the 

 thickness decreases very gradually. The members constituting 

 the formation in its typical development, beginning at the top, 

 are a pure semicrystalline, massive, very fossiliferous limestone, 

 a thick series of shaly limestone, and the basal series, thin bedded 

 dark limestones of the Tentaculite beds. On Catskill creek a 

 higher member of impure shaly limestone comes in above the 

 pure, massive beds, thickens rapidly and continues southward 

 to and through New Jersey. The Helderberg formation pre- 

 serves its typical characters with some local variations in thick- 

 ness to a few miles west of Cherry Valley. Then the upper 

 limestone beds thin out, and on the road from "West Winfiefd to 

 Litchfield, in the southwestern corner of Herkimer county, the 

 Pentamerus beds lie directly under the Onondaga limestone . . 

 The upper members of the Helderberg limestones . . . come in 

 again westward and are finely exposed at Oriskany Falls. 1 . .Here 

 120 feet of beds are exposed in and about the quarries, of which 

 50 feet are quite distinctively of the Tentaculite beds, 40 feet of 

 gray beds in greater part of Pentamerus limestone age, but 

 merging into the character of the lower beds, a few feet of 

 beds with mixed Pentamerus and shaly limestone fauna, and, at 

 the top, 25 feet of gray subcrystalline rock containing a shaly 

 limestone fauna. 25 miles west of Perryville, Madison co!, 

 this condition has continued, the lower members expanding appar- 

 ently at the expense of the Pentamerus beds and the upper 

 members giving place to Pentamerus beds. At this locality the 

 Onondaga limestone was seen lying on a few feet of dark' gray 

 limestones containing Pentamerus, with a thin local intervening 

 layer of Oriskany at one point, which gave place to a great mass 

 of thin bedded gray limestone below. 



The different members preserve their distinctive characters 

 more or less, though there are occasional slight local variations. 



The so-called Scutella beds are the uppermost member south- 

 ward to near Catskill. They are light colored, coarsely semi- 

 crystalline, massively bedded, highly fossiliferous limestone 

 blotched with calcite replacement of fossils, of which the most 

 conspicuous is the so-called Scutella. These are the cups or pelvis 

 of a crinoid, having a diameter in greater part from one to two 



1 See also Williams, S. G. The westward extension of rocks of the Lower 

 Helderberg age in New York, Am. jour. sci. 3d ser. 31: 139-45; abstract Proc. 

 Am. ass'n adv. sci. 34: 235, 236; Am. nat. 1886. 20: 373. 



