BY LKO A. COTTON. 



517 



of the "acid granite" with the older granite, but lies mainly 

 within the former. T!ie age of this " acid granite " has been 

 estimated as Permian. 



Tlie ore-deposits occupy two fractures, one trending E.5° N., 

 and the other, and more prominent, trending E.35°S. The 

 former lode is parallel to a well developed series of fractures in 

 the tin-bearing district some ten miles further east; the latter 

 has no representative system of fractures in the district. It is 

 inferred that the Borah Creek deposits are of a younger age than 

 the tin-deposits, for, had sucli a fracture as the Conrad Lode 

 existed at the time when these were formed, the active processes 

 accompanying their formation would assuredly have affected the 

 fracture. 



A series of faults bearing about N.15° W. have intersected 

 both lodes. A pretty example of the minor faulting in the King 

 Conrad Lode is represented in text-tig. 8. The only important 

 fault is that intersecting the Conrad Lode. This fault has 



Text-fig. 8. — Diagram illustrating faulting in the 

 King Conrad lode. F,fault. 



determined the position of several small streams. One of these 

 stream-courses may be noted in text-fig. 1, on which the sketch- 

 contours indicate how the fault has influenced the physiography. 

 This may also be seen in Plate xv., fig.l. 



