THE DEVONIAN SECTION OF ITHACA, N..Y. 589 



that Hall and Vanuxem were not in perfect agreement regarding 

 the correlation of the Genesee and Ithaca sections. Hall evidently- 

 believed that the Ithaca group of the annual reports was not distinct 

 from, but a lower portion of, the Chemung group. The equivalent 

 of the Portage or Nunda group according to that view would be 

 found below the Ithaca. Vanuxem, on the other hand, originally 

 intended "to unite the Sherburne and the Ithaca masses, not having 

 discovered in the district those leading characters by which they 

 could be readily distinguished. "^ Both authors evidently expected 

 the fossils, when fully studied, would solve the perplexity. 



In the final reports on the paleontology, which was chiefly pre- 

 pared by Hall, the Ithaca fossils were described as from the Chemung 

 group, thus perpetuating the view held by Hall in 1843. 



A review of the section and contained fossils was made by the 

 writer, and published in 1883 as Bulletin No. j of the United States 

 Geological Survey.^ In that paper it was shown that the fauna 

 of the Sherburne portion of the section below the Ithaca group 

 was present also above the latter; that there are 600 feet or more 

 of strata separating the Ithaca from the base of the Chemung; and 

 that the Ithaca and Chemung faunas are distinct. 



The investigations recently undertaken, in preparing the areal 

 map of the Watkins Glen quadrangle, have confirmed the correct- 

 ness of these points and have demonstrated more clearly the true 

 correlation of the two sections. It has been shown that, upon 

 passing westward from the Ithaca section, the molluscan fauna 

 characteristic of the Nunda formation prevails throughout the whole 

 1,300 feet of strata following the Genesee shale, with (at the head 

 of Seneca Lake) only a sparse representation of the Ithaca fauna 

 appearing in a few narrow beds in the lower portion of the section. 

 West of Seneca Lake scarce a trace of the Ithaca fauna is discovered, 

 but, when present, it is always below the first appearance of the 

 Chemung fauna. The fauna in the Grimes sandstone of the Naples 

 section reported by Clarke and Luther appears to contain a trace 

 of the Ithaca fauna. ^ 



1 Report of Third District, p. 171. 



2 Henry S. Williams, "On the Fossil Faunas of the Upper Devonian along the 

 Meridian of 76° 30' from Toinpkins County, N. Y., to Bradford County, Pa." 



3 New York State Museum, Bulletin No. 63, p. 63. 



