70 Diorites and Granites of Swift's Creek. 



the regional metamorphism, to be from twenty to sixty 

 chains. 



The several zones may be defined as follows: — 



1st zone (intimately connected with the intrusive rocks)> 

 aplite. 



2nd zone, hornfels (compact and schistose). 



3rd zone, indurated, wrinkled or silky slates, and sand- 

 stone. 



Of these, the first is by far the narrowest, and is only of 

 local occurrence. No hard and fast boundary can be drawn 

 between the second and third zones, as they are connected 

 by varieties. 



