GEOLOGY OF THE WEST POINT QUADRANGLE, NEW YORK I23 



wliich would be expected to be represented' in the Highlands if any 

 occur there. 



The different large units were compared with this member, with a 

 good deal of care and with enough success to warrant the suggestion 

 that the Storm King granite of the Highlands is practically identical 

 in petrographic character and geologic position with the syenite of 

 the Adirondacks. 



d The younger intrusives — Keweenawan ( ?) 



Occasional basic dikes ranging from camptonite to diorite and dia- 

 base are said to be characteristic of the Adirondacks, cutting all other 

 formations. They are supposed to correspond in age to the Kee- 

 weenawan of the Lake Superior region. 



Basic dikes of similar general composition and structural rela- 

 tion are also found in the Highlands. They cut the Storm King 

 granite in numerous narrow irregular stringers quite independently 

 of any of its primary or recent structures. These are essentially 

 dioritic in composition, but others of slig'htly different habit and 

 composition are found at other points. There is little doubt but 

 that these correspond in all essential respects to those of the Adiron- 

 dack region and the correlation is, therefore, satisfactory in respect 

 to this division also. 



c Metamorphics of obscure relation 



These do not appear to be represented in the xA.dirondacks, but in 

 the Highlands region a curiously obscure series of schists, crystalline 

 limestones and quartzites exhibit such marked dift'erences from the 

 regular well-known Cambro-Ordovician sediments that it is difficult 

 to escape the belief that they are really much older and properly 

 belong to the Precambrian series. This is the essence of the problem 

 of correlation referred to as the second item in the introductory 

 statement at the head of this chapter, that is, the Hudson River- 

 Wappinger-Poughquag comparison with the Manhattan-Inwood- 

 Lowerre series. 



This will be discussed under a separate head. All that need be 

 said about it in this connection is that the lack of correspondence 

 between the two districts, the Highlands and the Adirondacks, in 

 this respect does not modify materially the identifications and corre- 

 lations determined for the other members of the series already 

 described. But it does introduce a problem of relative age which 

 is of more than passing interest. For example, the very intimate 

 association of certain igneous members with the Manhattan-Inwood- 

 Lowerre series indicates that at least some of the granite invasions 



