GEOLOGY OF FRANKLIN COUNTY 105 



at all, but of the nature of a mammoth auge, an uncrushed portion 

 of the original rock whose granulation and stretching produced 

 the gneiss: The brown gneiss and anorthosite taken together 

 furnish a combination which resembles extraordinarily some of 

 the augen gneiss exposures along the Kacquette already described. 

 We can not answer these queries at present. In rocks so meta- 

 morphosed and changed the precise nature of such exposures as 

 these is seldom clear. 



Syenites. While the presence of great bodies of gabbroic in- 

 trusive rocks in the Adirondacks has long been known, it is only 

 very recently that evidence of similar intrusions of syenitic rocks 

 has been forthcoming. 1 This is for the simple reason that the 

 rock is by no means so easy of discrimination, being highly varia- 

 ble, usually gneissoid, weathering much more readily, and in 

 weathered condition closely resembling other rocks of apparently 

 wholly different relationships. 



These rocks are widely exposed in Franklin county. When 

 fresh they are of green or greenish gray shades, of considerable 

 variation in grain, though never presenting very coarse phases 

 comparable to the anorthosites, and usually of markedly gneissoid, 

 or else of linear structure. While there is often evidence of cata- 

 clastic structure, it is exceptional that any considerable feldspar 

 augen remain, and usually considerable recrystallization has 

 taken place. The contrast with the anorthosites in these respects 

 is so marked that some explanation must be sought in an original 

 difference between the two rocks, as they are of about the same 

 age and have therefore been metamorphosed under similar condi- 

 tions. It is thought to be due simply to an original difference in 

 coarseness of crystallization, the excessive coarseness of the 

 anorthosites rendering complete granulation a matter of much 

 greater difficulty. 



As is the case with all the intrusive rocks of the district, com- 

 paratively massive cores of less changed rock are of not un- 

 common occurrence. The most foliated rocks are those with con- 



iSmytb, C. H„ jr. Bui, geol, soc> Araer. 6:271-74. 



17th an. rep't N". Y. state geologist. 1897, p, 471-486. 



Cushiug, H. P. Bui. geol. soc. Amer, 10 : 177-92 



