370 NEW TOBK STATE MUSEUM 



Wm. C. Clarke, E. M. The clay localities were mapped by Mr. 

 Heinrich Ries,* the oil pools by Messrs. C. A. Ashburner and D. 

 Van Ingen, the salt wells by R. D. White, Jr., C. E., and the 

 gypsum quarries by "Wm. C. Clarke, E. M. The other mineral 

 localities were mapped by the author. 



In preparing the base, various practical difficulties had to be 

 met. Among these were the lack of accurate information con- 

 cerning the boundaries of the Chemung and Catskill formations 

 in New York, the impossibility of undertaking any new field 

 work, and the lack of sufficient funds to permit of more than fif- 

 teen printings in the press work of the map. It has, therefore, 

 been necessary to emphasize the economic character of the map 

 rather than the geologic character, to associate in color, rocks of 

 similar economic or lithologic features, and for lack of informa- 

 tion and funds for printing, to indicate without differentiation 

 the great mass of sandstones, shales and conglomerates included 

 between the base of the Portage and the top of the Catskill. 



When the large geologic map of New York, now in prepara- 

 tion by the State Geologist, is published and distributed, there 

 will be a definite expression of opinion on the boundaries of 

 these formations, but at present there is no official presentation 

 of the subject. 



The map will be found in the pocket of the cover of the bulle- 

 tin and the legend will explain the various tints and symbols used. 



Geologic Map of Westchester and New York Counties. 



Since the scale of the State economic map is not sufficiently 

 large to give in detail the areas of building stone, in New York 

 and Westchester counties, a map of that region is published 

 on a scale of four miles to one inch. This map is based on the 

 studies of the author and shows the present state of geologic 

 knowledge in that region. 



Economic Minerals of New York. 

 Under this head are described the minerals of New York 

 which are commercially important. So far as possible a directory 

 of the producers has been prepared for each mineral product. 



* Bulletin of the New York State Museum, No. 12. 



