Phenomena of Granite Veins. 



495 



was injected into an open fissure. Hence too we must be cautious in 

 imputing contortions in mica siate, even in the vicinity of granite 

 veins, to their eruptive force. 



(37) Granite Vein in Mica Slate ; Conway. 



No. 38 was sketched only 100 rods northeast of the congregation- 

 al meeting house in Conway. It represents two granite and several 

 quartz veins, in coarse micaceous limestone, a, a, appears to have 

 been the oldest granite vein, and is a foot wide on the right hand side 

 of b, b, and 20 inches at the other extremity. This is intersected by 

 another granite vein, b, b, and the two extremities are removed asunder 

 42 inches, c is a curved branch of this vein : b, b, is from 12 to 18 

 inches wide. 5, 5, s, s, s, s, s, are quartz veins, from half an inch to 2 

 inches wide, and one of them it will be seen, intersects both the gran- 

 ite veins ; and, therefore, these quartz veins appear to have been of 

 posterior origin to both the granite veins, d, and g, are masses of mi- 

 ca slate, with which rock the micaceous limestone, (that constitutes 

 the dark part in the sketch,) is interlaminated in the vicinity. The 

 direction of the layers of slate in the mass g, corresponds with that 

 of this rock generally in the vicinity : but in what manner the mass 

 d, should have been thrown at right angles to this direction it seems 

 difficult to imagine. It is obvious, however, that these granite veins 

 have produced great disturbance in this spot. 



