[Annals N. Y. Acad. Sci., Vol. XII, No. 6, pp. 11310116, July 8, 1899.] 



ORIGIN OF THE WHITE AND VARIEGATED 



CLAYS OF THE NORTH SHORE OF 



LONG ISLAND. 



By Frederick J. H. Merrill. 



(Read January 19, 1899.) 



In 1883, during a study of the Cretaceous and Tertiary clays 

 of the north shore of Long Island, the writer became interested 

 in finding a solution of the problem of their origin. Through 

 the last fifteen years various items of geologic evidence have 

 been carefully collected which, with the help of chemical analysis, 

 make it possible to present a satisfactory demonstration of the 

 fact that the white and variegated clays in question are derived 

 from the residuum of the crystalline limestone of Lower Silurian 

 age which forms an important part of the crystalline terrane of 

 Westchester county, N. Y. and, by its solution in connection 

 with subsidence of the land, has given existence to the navigable 

 channels which surround Manhattan Island and to the great 

 waterway of Long Island Sound. 



In 1889 the attention of this Academy was drawn to the 

 occurrence of some highly colored miaterial resembling clay 

 which had been observed in Morrisania in excavating for the 

 readjustment of the railroad tracks. Dr. D. S. Martin collected 

 some specimens of this which were exhibited to the academy in 

 connection with a paper read jointly by Dr. Martin and myself.^ 



In this paper it was shown that the seeming clays were re 

 sidual products from the decomposition of the crystalline lime- 

 stone which underlies the valley occupied by the tracks of the 

 New York and Harlem Railroad Co. A few years later. Pro- 

 fessor Kemp called attention to some specimens of similar ma- 

 terial from the Blackwell's Island tunnel, the bottom of the 



iRef. Trans. N. Y. Acad. Sci., Vol. IX, p. 45-46, 1889. 



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