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NEW YORK STATE MUSEUM 



oldest limestones are very impure. At Jerome Park reservoir they 

 carry an abundance of chondrodite and many unusual minerals, 

 such as actinolite, sphalerite and galenite. 



It is fairly certain that the gneiss series in southwestern New 

 York can best be regarded as a unit formation, the basis of which 

 is a metamorphosed sediment into which are intruded in a highly 

 complex manner igneous masses of various kinds and sometimes of 

 so large amount as to wholly obscure the original type. In some 

 localities these igneous masses largely predominate and may merit 

 local names but in all cases seen they give evidence of being 

 distinctly younger than the associated recrystallized sediments. 



An additional complexity has been observed in the vicinity of 

 Brewster in the Carmel quadrangle on the southeast margin of 

 the Highlands. Several narrow but remarkably continuous strips 

 of limestone occur in the schist. The most reasonable explanation 

 of them is that they are interbedded with the Manhattan schist. All 

 of the crystalline formations have been traced to the State line in 

 this vicinity, crossing the border into both Danbury and Ridge- 

 field, Conn. In comparing the formations of the New York side, 

 which have been followed in this investigation continuously from 

 their type localities in New York city, with the new (1906) areal 

 geologic map of Connecticut, the following points of correlation 

 are established: 



1 Two belts of crystalline limestone known on the New York 

 side as Inwood limestone continue into Connecticut, the one into 

 Danbury and the other into Ridgefield, as " Stockbridge " lime- 

 stone. 



2 Two belts of older gneisses, considered on the New York 

 side as equivalent to the Fordham gneiss, continue into Connecticut 

 as the " Becket " gneiss. 



3 One belt of schist, somewhat more complex than usual by 

 reason of intrusions, known as Manhattan schist on the New York 

 side, continues into Ridgefield, Conn, but on the Connecticut map 

 is not differentiated from the " Becket " gneiss. 



In the Poughkeepsie quadrangle the work of areal survey has 

 been carried on by Prof. C. E. Gordon. This quadrangle embraces 

 a portion of the Highlands of southeastern New York, known 

 generally as the Fishkill mountains, which on the north are over- 

 lapped by and faulted with the lower Paleozoics which extend 

 northward in the Hudson valley. Frequently the Highland mass 

 has overridden the newer strata and presents today many anomalous 

 relationships with the latter. From these, clearly marked and 



