Prosser — Hamilton and Chemung Series. 



145 



layers are separated by shales. One layer in the upper part of the quarry is 

 two feet thick, and another near the bottom is u finer-grained stone twenty- 

 seven inches in thickness. Similar greenish-grey sandstones continue to the 

 top of the hill some fifteen feet higher, 567 feet above the creek level or 

 approximately 1,557 feet A. T. Below the base of the red shales, 401 feet 

 above the creek, in the above section, fossils are very rare for a thickness of 

 252 feet, in that portion of the section that is indicated as A 4 and A 3 . Pro- 

 fessor Clarke observed that in the Crandall quarry, the base of which is 465 

 feet above the river, "fossils are exceedingly and remarkably rare through- 

 out," but he was fortunate in finding a few in one of the flagstones, and they 

 are here listed : " Palwoneilo emarginata, small form ; Nuctdites lirata, small 

 form, and Leda diver m. After a long search the soft green shales produced 

 a single specimen of a small Orthoceras or ColeolusP 1 This outcrop is less 

 than twenty-five feet below the fossiliferous red shale. These sections show 

 very clearly the gradual transition from the fossiliferous blue shales and 

 sandstones of the Ithaca formation to the coarser greenish-grey sandstones and 

 argillaceous red and green shales of the Oneonta formation, the conditions of 

 wliich were unfavorable to marine life. Farther east these conditions began at 

 an earlier period so that it is almost impossible to draw a synchronous line of 

 separation between the Ithaca and Oneonta formations when followed from 

 the Chenango valley eastward into Schoharie and Albany counties. 



The first heavy greenish-grey sandstones have been considered the base 

 of the Oneonta formation by some geologists, while others have placed the 

 lowest red shales there. It seems probable that in either case the line will be 

 a somewhat variable one. Apparently Clarke considered the base of this 

 formation defined by the "light grey-green sandstone 11 of the Hale quarry, 2 

 northwest of Norwich, which is 510 feet above the river level. Possibly it 

 might be as well to regard the red shales with the fossil fish remains eighteen 

 feet lower as the base, although, as previously stated, the line will vary in 

 position when followed for some distance. If these red shales are called the 

 base of the Oneonta formation, then in the high hill west of Norwich and the 

 Canasawacta creek, the Ithaca formation has a thickness of 490 feet, show- 

 ing its entire thickness to be greater than 500 feet for the Chenango valley. 

 It is to be recalled that a thickness of 450 feet has been assigned to \\w rocks 

 of the latter formation in the vicinity of Ithaca. 3 



1 Thirteenth Annual Report State Geologist [New York], p. 53(i. 



2 Ibid., p. 536, 537. Darton states that in Albany county he assumed the base of the Oneonta forma: ion to be " at the bottom 

 of the lowest red shale meml er;" ibid., p. 240. 



3 Transactions American Institute of Mining Engineers, Vol. XVI., p. 945. 



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