New York State Museum Bulletin 



Entered as second-class matter November 27, 1915 at the Post Office at Albany, N. Y., 



under the act of August 24, 1912. Acceptance for mailing at special rate of postage 



provided for in section 1103, act of October 3, 1917, authorized July 19, 1918. 



Published monthly by The University of the State of New York 



Nos. 225, 226 ALBANY, N. Y. September-October 1919 



The University of the State of New York 

 New York State Museum 



John M- Clarke, Director 



GEOLOGY OF THE WEST POINT QUADRANGLE, 



N. Y. 



By CHARLES P. BERKEY AND MARION RICE 



PREFACE 



The West Point quadrangle is the only one in southeastern New 

 York whose geology can not be appreciated at all without some 

 knowledge of the most obscure phases of metamorphism, mag- 

 matic differentiation and the processes by which rocks may come 

 to represent mixed types. Some of these fields are not well under- 

 stood even by the most experienced workers and others furnish 

 ground for much difference of opinion and interpretation. Many 

 of the problems of origin, history and correlation are surrounded 

 by obscurity and exceptional difficulty. Some of these are matters 

 that workers in the average region do not encounter at all. 



On this account the West Point report deals at much greater 

 length than would otherwise be advisable with debatable and theoreti- 

 cal questions, such as the discussion of processes of origin, the 

 methods of rock modification, the mechanics of structural con- 

 fusion, and comparison of alternative hypotheses. 



Metamorphic rocks, so extremely modified by a succession of 

 different influences that one can not now determine what they were 

 or how they are related, are common in this area, and igneous rocks 

 so variable in character, so complex in internal structure and so 

 confused in all their relations that one can not now determine how 

 many separate units to recognize or what limits to give them, are 

 equally charactertistic. 



