318 New York at the World's Columbian Exposition. 



limestone at Eichfield Springs, in the town of Springfield at the liead 

 of Otsego lake and at Cherry Valley ; a similar error occurs in the 

 mapping of these limestones in Seneca county, where they are shown 

 in a straight belt between Seneca and Cayuga lakes, far to the south 

 of Seneca outlet, although Prof. James Hall reported the occurrence 

 of the upper Helderberg limestone on Seneca outlet west of Waterloo. 

 In the new map the two Helderberg limestones have not been difEeren- 

 tiated for three reasons : First, because the scale of the map was too 

 small to permit it; second, because the author had not sufficiently 

 accurate information to enable him to separate them, and, thirdly, 

 because, the map being chiefly economic, it seemed best to represent 

 the two limestones in one belt. 



In addition to the text of the reports the following published maps 

 have been incorporated: 



Geological maps of Jefferson and Clinton counties, by E. Emmons ; 

 a geological map of Ontario county, by J. M. Clarke ; a geological map 

 of Yates county, by B. H. Wright ; a geological map of Onondaga 

 county, by Geo. Geddes ; a sketch map .of , the Mohawk valley, by 

 James Hall ; a geological map of Washington, Rensselaer and Columbi* 

 counties, by C. D. Walcott ; geological maps of parts of Dutchess and 

 Columbia counties, by J. D. Dana and W. B. Dwight ; a geological map 

 of parts of Orange and Ulster counties, by John C. Smock ; a map of 

 Richmond county, by IST. L. Britton, revised by C. A. Holiick. The 

 work of T. Nelson Dale, in Rensselaer county, has also been used. 

 JVIcFarlane's Geological Railway Guide has been freely consulted. To 

 Prof. James Hall, State Geologist, the thanks of the author are due for 

 information concerning the geology of many localities. 



The localities of iron mines are chiefly taken from the published 

 map of Prof. J. C. Smock. The stone quarries are from Prof. Smock's 

 map, with additions by Wm. G. Eberhard, E. M., and 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 concerning the 

 boundaries of the Chemung and Catskill formations in New York, the 

 impossibility of undertaking any new field work, and the lack of suffi- 

 cient funds to permit of more than fifteen printings in the press work 

 of the map. It has, therefore, been necessary to emphasize the eco- 

 nomic character of the map rather than the geologic character, to asso- 

 ciate in _ color rocks of similar economic or lithologic features, and for 

 lack of information and funds for printing to indicate without differen- 

 tiation the great mass of sandstones, shales and conglomerates included 

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



When the large geological map of New York, now in preparation 

 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. 



