Prosser — Hamilton and Chemung Series. 



147 



exception — that is, species that are known to occur below the second black 

 Devonian shale." 1 



The writer referred to this fact in 1893, 2 and Clarke, in 1894, stated it 

 very clearly. In describing the faunas near Norwich, Clarke wrote: "If, 

 however, there exists a palpable difference between the faunas at B and B, 

 [quarries one mile northwest of Norwich |, and that of the typical upper 

 Hamilton shales in regions where the Tully limestone is present, they may be 

 reduced to the existence in the former of Actinopteria zeta, and the not 

 infrequent occurrence of Spirifer Tmsasi/rialis ; " 8 and again " the predom- 

 inant traits of the fauna are Hamilton; its extra-Hamilton species are rare, 

 especially in the lower parts of the series." 4 



As will be seen from the above statement, the rocks near Norwich con- 

 tain a considerable number of species that occur in the Hamilton formation, 

 but have not yet been reported from the Ithaca formation as exposed at its 

 typical locality, Ithaca. Since this fauna is more decidedly Hamilton than 

 the typical Ithaca, which is the general condition at least from the Chenango 

 valley eastward, the question may arise whether eventually it may not be 

 better to designate this formation by a name that will refer to a locality at 

 which the faunal and stratigraphic conditions are more nearly representative 

 for the eastern and greater extent of the formation. 



While considering this portion of the Chenango valley section it is 

 important to remember that in most of the recent papers relating to the 

 geology of this valley, the Sherburne formation has been overlooked. As 

 described above in Nigger brook, in the southern part of Sherburne township 

 (XIX C 2 ), in the lower part of the Sherburne formation is a Goniatites fauna 

 that is probably an eastern extension of the Cepludopod stage (C 1 ) described 

 by Dr. H. S. Williams as occurring in the lower Portage. 5 The writer called 

 attention to this formation in 1887, 6 although at that time, on account of in- 

 sufficient data, its thickness was underestimated, and again in 1893. 7 The 

 Sherburne formation in the Chenango valley is 250 feet in thickness and the 

 Ithaca formation at least 500 feet, making a total thickness, for the rocks, 

 from the top of the Hamilton formation to the base of the Oneonta, of more 

 than 750 feet. This gives a thickness of some 1,250 feet for the Sherburne, 



1 Proceedings American Association for the Advancement of Science, Vol. XXXIV., p. 229; also see the plate of " Meridional 

 sections of the Upper Devonian deposits of New York, Pennsylvania and Ohio," section IX. 



2 American Journal of Science. Third series, Vol. XLVI., p. 225. 



3 Thirteenth Annual Keport State Geologist [New York], p. 5&5. 

 < Ibid., p. 554. 



5 Proceedings American Association Advancement of Science, Vol. XXXYI., p. 226. 



6 Ibid., p. 210. 



7 American Journal of Science, Third Series, Vol. XLVI., pp. 221, 222, 224. 



