366 



SCIENCE. 



[N. S. Vol. XXIV. No. 612. 



of classification and nomenclature proposed 

 was the result of a resurvey of the forma- 

 tions examined in preparation of the map 

 and folio of the Watkins and Catatonk 

 Quadrangles now in preparation. The sec- 

 tion is the standard section of the New 

 York Devonian as originally defined and 

 described by Vanuxem and Hall in 1842- 

 1843. The revision of the classification and 

 nomenclature is based upon a critical study 

 of the composition, sequence and range of 

 the fossil faunas of the Watkins and Cata- 

 tonk Quadrangles. The thicknesses are 

 estimated as for a generalized section pass- 

 ing through the rocks at Ithaca, N. Y. 



The taxonomic classification into series, 

 formations, members and lentils, is in ac- 

 cordance with the rules of the U. S. Geo- 

 logical Survey published in the 24th An- 

 nual Report for 1902-1903. 



The following chart expresses in brief 

 the classifications and nomenclature pre- 

 sented, the new names having been accepted 

 by the committee on geologic names of the 

 U. S. Geological Survey. 



The principal changes affecting nomen- 

 clature are the following: viz., the Nunda 

 shale and flagstone formation is the strati- 

 graphic equivalent of Hall's Portage or 

 Nunda group, the standard section of which 

 is found in the Genesee Valley. The term 

 Portage was used by Hall for the sand- 

 stone member at the top of his Portage or 

 Nunda Group as well as in the name of the 

 other group. Of the two synonyms the 

 first (Portage) is left to be applied in its 

 specific sense to the Portage sandstone 

 member, and Nunda is retained for the 

 formation name. 



The lithologically discriminated members 

 of the Nunda characteristic of the Genesee 

 Valley section {i. e., Cachaqua, Gardeau 

 and Portage) are not distinguishable in the 

 Ithaca section. The subdivisions in the 

 latter section are the Sherburne flagstone, 

 the Ithaca shale and the Enfield shale mem- 

 hers. The first of these is the equivalent 

 of the Sherburne flagstone of Vanuxem; 

 the second is the typical Ithaca group of 

 Hall and later writers: the third is the 



SCHEME OF CLASSIFICATION AND NOMENCLATURE OF THE GEOLOGICAL SECTION PASSING THROUGH 



ITHACA, N. Y. 



