604 WILLIAM J. MILLER 



If, however, we regard the foliation as essentially a sort of flow 

 structure, such phenomena are readily accounted for as due to 

 local variations in the magmatic currents. 



Curving strike of foliation. — Still another piece of evidence, 

 though less commonly shown, is the existence of certain broad, 

 sweeping curves in the foliation of syenite or granite. The North 

 Creek, Lake Pleasant, and Long Lake geologic maps show such 

 features. When larger areas of the Adirondacks are mapped in 

 detail, it is probable that more and better examples will be brought 

 to light. 



An excellent case of curving of foliation on a large scale is in the 

 Panther- Snowy mountain mass above described as extending nearly 

 across the southern portion of the Blue Mountain sheet and the 

 northern portion of the Indian Lake sheet. The great mass of 

 syenite shows an almost perfect radiation of foliation dips from its 

 center toward the west, north, and east. The only reasonable 

 explanation of such an arrangement of dips is that the foliation was 

 produced as a flow structure in the uprising magma, the most rapid 

 currents having been toward the center of the mass. In the writer's 

 opinion, such a large-scale curved arrangement of foliation strikes 

 and dips not only cannot possibly be explained as due to lateral 

 pressure, since the foliation would then everywhere be practically 

 at right angles to the pressure, but also conclusively proves that 

 no severe compression ever affected the syenite. 



Nearly thirty years ago, in his study of the Rainy Lake region, 

 Lawson described a somewhat similar curved foliated structure in 

 granite gneiss and said regarding its origin : " The simplest explana- 

 tion that suggests itself to account for the structure is that of an 

 uprising force acting on a plastic mass (pasty magma), such force 

 acting with greatest intensity in the vertical line which would 

 correspond to the axis of the cone or dome." 1 



A similar type of structure appears to be common in the 

 Haliburton-Bancroft area of Ontario as described by Adams and 

 Barlow, who say: "Within the batholiths themselves the strike 

 of the foliation follows sweeping curves, which are usually closed 

 and centered about a certain spot From these central aieas 



1 A. C. Lawson, Ann. Rep. Geol. Surv. Can. (N.S.), III (1887-88), 116. 



