624 FRANK D. ADAMS 



ment in the former of little strings or irregular patches of coarsely 

 crystalline white calcite, usually following the bedding planes. These 

 become larger and more numerous on going north in the area toward 

 the granite intrusions, until eventually the whole are transformed into 

 great bodies of white marble. Here and there through this marble, 

 where it is very thick, small remnants of the original blue limestone 

 can occasionally be found. 



Enormous bodies of nearly pure limestone or marble occur in 

 many parts of the area, but elsewhere it becomes impure, owing to the 

 presence of numerous scales and granules of various silicates dis- 

 tributed through it, or owing to the appearance of numerous little 

 bands of silicates representing impurities in the original limestones, 

 which, under the influence of metamorphism, develop into gneisses 

 and amphibolites of various kinds. Where these little gneiss or 

 amphibolite bands become increasingly abundant, the limestone 

 passes over into paragneiss or into some one of the varieties of 

 amphibolite. 



The limestone in what may be called its usual development, that 

 is, in its highly crystalline form, is a white, cream-colored, or pinkish 

 marble, and is generally very coarse in grain. The little grains or 

 scales of foreign minerals scattered through it are usually arranged 

 so as to indicate the lines of the original bedding. No less than 

 thirty-seven species of these minerals have been found in the lime- 

 stones in this area, of which phlogopite, malacolite, serpentine, 

 scapolite, graphite, and pyrite are the most common. 



That the limestone has in many places been subjected to great 

 movements can be distinctly seen on the face of any high cliffs or 

 where other large surfaces of the limestone are exposed. Here the 

 interstratified bands of gneiss or amphibolite can be seen winding 

 to and fro over the exposed surface, often folded back upon them- 

 selves or broken into fragments which have become widely separated 

 from one another by the movements, the more plastic limestone hav- 

 ing flowed in between them, the rock often in this way taking on the 

 appearance of a coarse conglomerate. 



The quartziles. —Quaitzite is not common in this area. Where 

 it occurs it is found interstratified with the crystalline limestones and 

 rusty weathering paragneisses. It is well foliated and rather fine 



