Veins in Sienite. 



459 



present ridges on the surface of the rock an inch or two in width ; the 

 epidote being a mere line in thickness. These veins have cut off the 

 feldspar vein and produced an echellon movement of the central part. 

 € is a nodule of some other rock enclosed in the sienite and cut off by 

 the feldspar vein. 



Veins in Sienite : Whately. 



We have here only two successive formations of granite, though 

 the epidote veins were protruded at a third epoch. And the lateral 

 movement of the sienite by these veins, indicates, it seems to me, thac 

 although the rock was consolidated at the surface, yet not probably to 

 any great depth, when these epidote veins were injected ; otherwise I 

 cannot conceive how such a movement could have been produced. 

 A slight heaving of the waters of a stream would break and produce 

 various slides in the ice on its surface when it was quite thin : but let 

 the river be frozen nearly to the bottom, and such movements would 

 be produced with great difficulty. 



The following sketch was formerly inserted in the 6th volume 

 of the American Journal of Science : but such a curious succession 

 of echellon movements have been produced in the granite veins a, a, 

 &c, b, b, &c. by the epidote veins d, d, &c, that I thought it deserved 

 a place here. The sides of the rock represented are about 4, 6 and 

 10 feet, c is a fragment of some stratified rock imbedded in the sienite 

 and cut through by the vein b. The width of the granite vein va- 

 ries from one to 2 1-2 inches. 



