92 



Report of the State Geologist. 



Ithaca group to the Chemung, stating that the reason for uniting the two 

 groups is "the impossibility of identifying thein as distinct by any character- 

 istic fossils." 1 To the Portage or Nunda group Professor Hall referred the 

 Cashaqua shale, Gardeau and Portage groups, and the Sherburne flagstones of 

 the annual reports. 2 



On the geologic map of New York, published in 1842, and the agricul- 

 tural and geologic map, published in 1844, the Port age and Chemung groups 

 were colored together, the Ithaca group not being mentioned. 



Emmons prepared a report on the "Agriculture of New York," and 

 Chapter VI. of Vol. I. is devoted to a classification and description of the 

 rocks of the State. 3 In describing those formations which are under special 

 consideration at present, Emmons used the heading, " Portage, Ithaca and 

 Chemung groups of the central counties of New York." 4 



It seems that Emmons recognized a considerable difference between the 

 Ithaca and typical Chemung, as shown by the fossils collected at several 

 places, but that he was not prepared to actually separate the Ithaca from the 

 Chemung group. In respect to this classification Emmons said: " It would 

 seem, from a comparison of facts developed by a careful examination, that the 

 Ithaca group is not equivalent to the Chemung as it is developed at the 

 Chemung narrows, but rather that it is beneath, and situated between the 

 Portage and Chemung groups. There is, however, no necessity for separating 

 the Ithaca from the Chemung group ; it is more simple to regard the masses 

 as parts of one series, in which the inferior and superior may differ in many 

 points." 5 



Professor Hall, in the descriptions of the fossils from the Ithaca group at 

 Ithaca and other localities, has adhered to the classification in his final report, 

 and referred them to the Chemung group. 6 



Views of More Recent Contributors. — The next important contribution to 

 the literature of the Ithaca group was the bulletin of Prof. Henry S. Williams, 

 on " The Fossil Faunas of the Upper Devonian," which bears the date of 1884. 

 In this paper the characteristics of the rocks near Ithaca and southward into 

 the typical Chemung of southern New York and northern Pennsylvania are 

 described, accompanied by lists of fossils from numerous exposures. As a 



i Geology of New York. Part IV., p. 250. 

 » Ibid., p. m. 



3 This volume was published in 1840. and Chapter VI., which is called the " New York System," comprises 95 of the 371 pageB 

 Of the volume. 



* Agriculture of New York, Vol. I., p. 190. 

 s Ibid., p. 191. 



c Geological Survey, New York, Palaeontology, Vol. IV., Part I., 1867, Brachiopoda ; ibid.. Vol. v.. Part I.. Lamellibranchiata 

 L, 1881 ; ibid., II., 1885. 



