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NEW YORK STATE MUSEUM 



determination of the relations between the two, and the writer is 

 in doubt concerning them. But whether this is the same rock or 

 a different granite, it is so like the other in appearance and in 

 amount of metamorphisni, being mostly fairly coarse and with 

 numerous feldspar augen, that there can be little doubt of the 

 close relationship of the two rocks, and it may be safely stated 

 that the two, if distinct, have arisen from the same parent magma 

 and are not far separate in time. It is simply a question whether 

 differentiation has taken place where the rocks now lie or has 

 taken place beneath. 



Running northeast from Litchfield park are two big rock ridges, 

 pitching northwardly with gentle slopes, but breaking down in 

 tremendous cliffs on the southwest, which are constituted of a 

 reddish, coarsely gneissoid rock, grading locally into green patches 

 of unmistakable syenite, which the field relations and the thin 

 sections show to be nothing but an extra acid phase of the syenite 

 [pi. 17]. The rock approaches granite but is not as decisively 

 granitic as the previous rocks. It is however another instance 

 of the passage of the syenite into a granitic rock, and the special 

 interest which attaches to it comes from the fact that it is sur- 

 rounded on all sides by ordinary syenite and hence seems clearly 

 a central, acid differentiation of a syenite mass. 



Occasional local reddish gneisses appear in the syenite of some- 

 what different nature from the foregoing, and in these the color 

 change is not accompanied by much increase in acidity. A case 

 of the sort is met in the section at Little Falls, the rock in question 

 being a syenite full of feldspar augen, which has locally been so 

 mashed and stretched that the augen have become nearly or 

 entirely crushed, the product being a granular red feldspar which 

 has been squeezed out into flat lenses, often tailing out into the 

 rock as thin sheets of considerable extent. In some of these a 

 bit of uncrushed feldspar still remains, and all stages between 

 this extra mashed condition and the ordinary rock can be observed, 

 so that there can be no question of the origin of the granular red 

 feldspar; the origin of the color change is not manifest however, 

 since the augen themselves are by no means red. Furthermore, 

 the red color is confined to this portion of the rock, and the re- 

 mainder is still of the gray green of the ordinary syenite. It is 



