FOLIATION IN THE PRE-CAMBRIAN OF NEW YORK 607 



this statement by Leith, since anything like true schists are very 

 rare if not wholly absent' from the syenite-granite series. 



Significance of granulation. — Granulation of the rocks of the 

 syenite-granite series is of common occurrence. Most of the 

 mineral constituents are more or less granulated, though it is quite 

 the rule that the quartz shows the effects of crushing less than the 

 others. In the greatest bulk of the rock the cataclastic texture 

 shows itself by flattened or irregular lens-shaped quartz individuals, 

 and more or less lens-shaped broken feldspars, imbedded in a mass 

 of small broken feldspar grains together with some crushed quartz 

 and leaves of mica. In many cases more or less thoroughly 

 elongated and crushed hornblende or augite also occur. 



This granulation has usually been regarded as proof that the 

 rocks have been subjected to severe lateral compression and 

 crushing after their consolidation. Thus Smyth, keeping in mind 

 the frequent lack of crushing of the quartz, has said : " As the quartz 

 could hardly flow while the feldspar fractured, the conclusion is 

 obvious, and seems to be well grounded, that, in the case of the 

 quartz, there has been crystallization after the production of 

 cataclastic structure in the rock." 1 But does this prove the quartz 

 to be largely recrystallized or of secondary origin ? Could not 

 movements in the magma during a late stage of consolidation, and 

 before much quartz (the last to form) had- crystallized out, have 

 caused granulation of the earlier-formed crystals, while the quartz 

 would have been more or less unaffected ? In explaining the origin 

 of foliation in the granite-gneiss of the Thousand Islands region, 

 Cushing says: "The rock has been much crushed and somewhat 

 recrystallized under compressive stress, since it originally con- 

 gealed." 2 Now, while some granulation and recrystallization may 

 have taken place after the magma consolidation, it is by no means 

 a necessary inference that the granite has been much crushed and 

 principally foliated after it had congealed. Strong evidence against 

 severe compression of the Adirondack region has been presented in 

 this paper, while the best evidence points to the origin of the folia- 

 tion as essentially a flow structure developed under moderate 



1 C. H. Smyth, 15th Ann. Rep. New York State Geologist, 1895, pp. 488-89. 



2 H. P. Cushing, New York State Mus. Bull., No. 145, 1910, p. 102. 



