VOLUME XXV NUMBER 6 



THE 



JOURNAL OF GEOLOGY 



SEPTEMBER-OCTOBER 1917 



STRUCTURE OF THE ANORTHOSITE BODY IN THE 



ADIRONDACKS 



H. P. CUSHING 



Western Reserve University, Cleveland, Ohio 



Introduction. — In No. 3 of the current volume of this Journal 

 Dr. N. L. Bowen has discussed "The Problem of the Anorthosites " 

 in a very suggestive and important paper with whose general 

 thesis I find myself in quite hearty accord. It seems to me that 

 the process of formation of anorthosite, as there outlined, is quite 

 the most probable method yet suggested; and I am quite in agree- 

 ment with the explanation of the general protoclastic and granu- 

 lated textures which all large bodies of anorthosite exhibit. 



When, however, Dr. Bowen comes to consider the universal, or 

 usual, field relations between anorthosite and the accompanying 

 bodies of syenite, and suggests in that connection a structural 

 relationship of these rocks in the Adirondack region, the field 

 facts there, as known to me, seem to be in direct conflict with 

 certain features of that suggestion. The chief point on which we 

 differ does not seem to me in any way to vitiate his main argument, 

 but it does seem desirable to bring it out plainly. 



His argument is substantially as follows: that there is (a) an 

 intimate connection of syenite with anorthosite wherever the latter 

 is found, as shown by the abundance of rock types intermediate 



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