326 NEW YORK STATE MUSEUM 



concentric arrangement of the different rock varieties produced^ 

 usually with the most acid rock in the center and the most basic 

 in the peripheral portions of the mass; sometimes however the 

 reverse arrangement occurs, the basic rock being the central one- 

 This of course is in the large way, and insignificant local varia- 

 tions, such as are specially characteristic of gabbros, are not in 

 mind. Now both at Tupper lake and at Diana the gradation inta 

 granite appears to be a one-sided one, and with no apparent sign 

 of any tendency to concentric arrangement. At Tupper lake the 

 gabbroic phases of the syenite, so far as they have been noted, are 

 all in the vicinity of the anorthosite, while the gradation inta 

 granite is apparently confined to the south side of the mass, and 

 other granites appear in force beyond. This is certainly an un- 

 usual arrangement, and the cause, though not now manifest, may 

 perhaps be brought out by more detailed work, specially in the- 

 unexplored country to the south. 



Morris granite. There is one granite in the region which pre- 

 sents very definite characters, is generally found only in small 

 masses, plainly cuts all the rocks heretofore described and hence- 

 is likely the latest granite in the region, and to which for con- 

 venience of reference and because of its usmal easy recognition it 

 seems worth while to give a. name. Hence the term " Morris 

 granite " is suggested for it, because of the considerable exposures- 

 which occur cutting tte augite syenite on the west slopes of Mt 

 Morris, Franklin county. 



The rock is peculiar in thait it consists almost wholly of alkali 

 feldspar (mostly microperthite) and quartz. There is a trifling- 

 amount of hornblende and magnetite usually present, and occa- 

 sional minute apatites and zircons, but they sieldom form more 

 than 5fo of the whole. The feldspar is red in color, usually strongly 

 so. The rock presents both coarse and fine grained phases, and it 

 is the former which so characteristioally marks the rock. The 

 quartz is concentrated into long spindles or pencils, or else into 

 long flattened lenses, giving the rock a pronounced linear struc- 

 ture ; that is, the structure appears gneissoid on fractures parallel 

 to the spindles and not at all gneissoid on fractures at right 

 angles to them, since here the spindles present their rounded cros» 

 sections merely. Since the quartz percentage is high, these large 



