p 



STATE GEOLOGIC MAP OF 1901 33 



For the Adirondack area Professors Gushing, Kemp and 

 Smyth mapped in manuscript their respective areas of work, 

 much of which had been left uncovered by their published maps. 

 Several of the maps used in manuscript have since been pub- 

 lished. 



Manuscript maps by G. K. Gilbert, covering parts of the Upper 

 Silurian area of Niagara county and a revision by I. P. Bishop 

 •of parts of his map of Erie county were also used. 



Prof. W. B. Dwight contributed in manuscript the results of 

 his field, work in Dutchess county. 



In southeastern New York, field work by the writer and his 

 assistants furnished a large amount of unpublished material. 



Long Island was mapped in manuscript by Prof. J. B. Wood- 

 worth and his assistant, J. E. Woodman, as the result of 

 field work for the State Museum. Part of the area thus cov- 

 ered has since been described with accompanying maps in 

 Museum bulletin 48. 



NOMEJVCIiATURE OF NEW YORK GEOIiOGY 



In selecting names to "be applied to the formations shown on 

 the map the attempt has been made to render it as serviceable 

 as possible to the teacher and student by keeping its nomen- 

 -clature as close as possible to the mass of older textbooks now 

 in use. 



In so doing the editor has not followed in every case the latest 

 expression in terminology or classification, and has not under- 

 taken to decide the merits of any question at issue. 



Perhaps the most prominent question of geologic classification 

 in New York now under discussion is that of the systematic posi- 

 tion of the Helderberg limestone; namely whether it should be 

 regarded as Silurian or Devonian. Dr John M. Clarke, state 

 paleontologist, after exhaustive study, has expressed the opin- 

 ion that in this formation fossils of Devonian aspect appear and 

 that it should, consequently, be included in the Devonian system. 

 Prof. H. S. Williams, attacking the question from another point 

 of view, in his studies of the Paleozoic formations of Maine,^ 



'U. S. Geol. Sur. Bui. 165, p. 56. 



