FETTKE, MANHATTAN t^CHI^T OF NEW YORK 199 



In 1878, Professor J. S. NewbeiTy^" stated that it was his opinion that 

 the formations underlying Manhattan Island were Laurentian in age, 

 although he was not in a position to make a positive assertion to that 

 effect. The fact that a mottled serpentine^ ^ occurs on Manhattan Island 

 which very closely resembles the Moriah marble of the Adirondacks which 

 is known to be of Laurentian age he regarded as very strong evidence of 

 the pre-Cambrian age of the former. 



The most important contribution, however, to our knowledge of the 

 formations of southeastern New York State after Mather had published 

 his final report on the first geological district was the result of the work 

 done by Professor James D. Dana in this region during the 70's. In 1880 

 he published a paper^^ on the geological relations of the limestone belts 

 of Manhattan County. After a careful and detailed study of the lime- 

 stone belts both to the north and to the south of the Highlands, he came 

 to the conclusion that they were of the same age. He states that the 

 limestones and adjoining schists of Westchester County are younger than 

 the Highland Archean and are probably Ordovician and in part Cambrian 

 in age. He considers that Westchester County was topographically the 

 southern part of the Green Mountain elevation, the axis passing along the 

 Connecticut-New York boundary line and extending through Manhattan 

 Island. He also pointed out that the grade of metamorphism followed 

 the same rule south as north of the Highlands, being of greatest intensity 

 to the south and eastward, since the limestones and associated phyllites 

 northwest of Peekskill were the least metamorphosed of those occurring 

 south of the Highlands, while those of the central and eastern portions of 

 the county and in the western part also were usually very coarsely crystal- 

 line. The limestones at Verplanck and Crugers on the other hand have 

 only a moderately crystalline texture. They occupy an intermediate posi- 

 tion between the least crystalline and the more coarsely crystalline areas. 



James Hall in his report on the building stones of New York State^^ 

 in 1886 followed Dana and correlated the marbles quarried in West- 

 (thester County and those of Dutchess County, western Connecticut and 

 Massachusetts and Vermont. He placed them in the Quebec group. 



Professor James F. Kemp in a paper on the geology of Manhattan 



10 "The geological history of New York Islands and Harbor." Pop. Sci. Mthly., Vol. 13, 

 pp. 641-660. 1878. 



^ Trans. N. Y. Acad. Sci.. Vol. I, pp. 57-58. 1881-82. 



^ "On the geological relations of the limestone belts of Westchester County, New 

 York." Amer. Jour. Sci.. .3rd ser.. Vol. 20. 1880. pp. 21-32, 194-220, 359-375, 450-456 ; 

 Vol. 21, 1881, pp. 425-443 ; Vol. 22. 1881. pp. 103-119, 313-315, 327-335. 



i» "Report on building stones." 39th ann. rept. N. Y. State Mus. Nat. Hist., pp. 186- 

 225. 1886. 



