610 WILLIAM J. MILLER 



were the ease there would result considerable recrystallization and 

 granulation so that typical crystalloblastic or cataclastic textures 

 might be superimposed upon that resulting from primary con- 

 solidation." 1 



The possibility of some granulation and recrystallization in 

 the Adirondack intrusives after complete consolidation is admitted 

 by the writer, but, in view of the evidence above presented, such 

 processes must have had relatively little to do with the development 

 of the textural and structural features of the rocks. 



Cause of mineral elongation. — Still another matter to consider 

 briefly is the cause of the flattening or elongation of minerals in 

 the primary gneiss. Flattening or elongation of minerals, espe- 

 cially quartz and feldspar, are common in the Adirondack intrusives, 

 varying from rocks in which the phenomenon is scarcely noticeable 

 to others in which it is extremely developed. It is the writer's 

 experience that many such variations exist within short distances. 

 Quartz exhibits such tlattening better and more frequently than the 

 feldspars. The writer believes that the mineral flattening or elonga- 

 tion was caused essentially by crystallization in the magma under 

 pressure. Truemarr has recently presented considerable evidence 

 to show that elongation (and presumably flattening) of mineral con- 

 stituents by crystallization under differential pressure must often 

 have been a very important factor in the production of foliation of 

 primary gneisses. 



In the Adirondack syenite-granite series, quartz shows the 

 effects of flattening most because it was the last mineral to crystal- 

 lize out and hence was not subject to so many of the movements 

 in the magmas. Loughlin presents a similar argument regarding 

 the Sterling granite-gneiss of Connecticut as follows: "After crys- 

 tallization had become so far advanced that the rock became a 

 mass of feldspar crystals (plus a small amount of quartz) with 

 interstices tilled with still fluid quartz, the feldspars would suffer 

 strain, rotation, and slicing, and become a more or less granular 

 lens-shaped aggregate elongated in the direction of least pressure. 

 .... As the interstitial quartz began to crystallize, it would be 



1 J. D. Trueman, Jour. Geo!., XX (1912), 244. 



»/«<*., XX (1912), 235-42. 



