r62 NEW YORK STATE MUSESUM 



The above observations fall exactly in line with those detailed 

 in the present report. The aagite syenite is found grading into a 

 granite on the one hand; on the other, another granite is found, 

 and the writer's observations would indicate that this is later and 

 cute the syenite intrusively. This is certainly true of a granite 

 which can not be distinguished froim the main mass of the rock. 

 That the syenite is markedly younger than the Grrenville rocks is 

 also^shown, and to greater perfection than in any other locality 

 yet known in the Adirondacks. 



Relationship of the syenite and granite to anorthosite 



It would seem that there is substantial agreement between 

 Prof. Kemp and Prof. Smyth and the writer, that there are large 

 masses o:15 syenitic and granitic gneisses in the Adirondacks, 

 which are of igneous origin and younger than the Grenville 

 rocks. But, so far as the writer is aware, no observations bear- 

 ing on the relative age of the anorthosite as compared with the 

 syenite and granite have been put on record, aside from those 

 from the localities mentioned in this report. Here a locality has 

 been described in which there is an apparent transition from 

 anorthosite to augite syenite, though the outcrops are not suflS- 

 ciently numerous to permit of certainty in the matter ; another 

 locality has been described, where augite syenite appears in 

 considerable force invading anorthosite irruptively, and yet 

 others where augite syenite dikes cut the anorthosite. There 

 are also occasional granite dikes in the same rock. But the re- 

 verse phenomena have not been noted. The anorthosites cut 

 the Grenville rocks irruptively, but there is no evidence either 

 in the shape of contacts or of dikes to show that they are later 

 than the syenite. The evidence is conclusive that augite syenite 

 is present in the Adirondacks, which is closely related to the 

 anorthosite, but which is somewhat younger. 



While it has not been, and for the most part can not be shown, 

 that the different augite syenite areas in the region are all of 

 approximately the same age, there is, so far as the writer knows, 

 absolutely no evidence of difference in age, and the structural, 



