FOLIATION IN THE PRE-C AM BRIAN OF NEW YORK 599 



Describing the metamorphism of the Shuswap pre-Cambrian 

 series in the Canadian Rockies, Daly says: "It is clear that the 

 Shuswap series has not been seriously affected by dynamic meta- 

 morphism. The strata and most of the injected granites were 

 completely or almost completely recrystallized while the strata 

 lay nearly flat. In some localities the effects of dynamic meta- 

 morphism have been superposed on those due to previous static 

 metamorphism ." x 



Orientation of Grenville inclusions. — Another fact of importance 

 in connection with the origin of Grenville foliation is the occasional 

 occurrence of well-foliated inclusions of Grenville gneisses variously 

 oriented in the great intrusive bodies. Twenty years ago, in St. 

 Lawrence County, Smyth, noting irregular inclusions of black 

 gneiss in granite, said : "The two foliations, that of the black masses 

 and of the (granite) gneiss, range from parallel with, to perpendicu- 

 lar to, each other." 2 He also noted a similar arrangement of 

 Grenville laminated gneiss inclusions in syenite in Jefferson County. 

 The writer has observed similar phenomena on small and large 

 scales at various localities. Kemp has recently noted inclusions in 

 massive anorthosite and says: "The foliation of the fragments runs 

 in all directions, even in an area of a few square yards. The infer- 

 ence is drawn that the Grenville gneisses were already strongly 

 metamorphosed when the anorthosites entered." 3 It is thus clear, 

 in spite of the usual assumption to the contrary, that the foliation 

 of the Grenville could not have been the result of lateral pressure 

 brought to bear after, or even during, the intrusion of even the oldest 

 of the great igneous masses. 



General absence of granulation. — Another fact favoring a process 

 of essentially static metamorphism as opposed to that of dynamic 

 metamorphism is that the Grenville gneisses are, as a rule, com- 

 paratively little granulated. Some rather local granulation is 

 to be expected because of magmatic movements, especially where 

 Grenville masses have been crowded against the up welling magmas. 

 The great intrusive syenite-granite series is very notably more 



1 R. A. Daly, Geol. Surv. Can., Transcont. Excur. C 1, Guidebook 8, 1913, p. 132. 



2 C. H. Smyth, 15th Ann. Rep. New York State Geologist, 1895, p. 491. 

 •5 J. F. Kemp, Geol. Soc. Am. Bull., XXV (1914), 47. 



