688 C. A. STEWART 



Calkins, Eldridge, and Umpleby, or where seen by Professor 

 Livingston or the writer, is there any rock Hke this Cceur d'Alene 

 type, it seems evident that we are deahng with something more 

 significant than a single vast batholith underlying all of the state. 

 It is of course possible that the main Idaho batholith does under- 

 lie the Cceur d'Alene and neighboring districts at great depths, and 

 that the exposures of the Cceur d'Alene type are offshoots reaching 

 up into the overlying sediments and slightly differentiated. In 

 view, however, of the proximity and nearly equal elevation of the 

 Gold Hill and Thatuna Hills occurrences, I am inclined to regard 

 the Cceur d'Alene type as the result of a separate intrusion, con- 

 nected indeed in ultimate origin with the main batholith, but 

 nevertheless distinct from it. Very probably it should be classed 

 as a complementary intrusive, somewhat later than the main mass 

 but from the same source. If this be true, we may expect to find 

 monzonite of the Cceur d'Alene type cutting the micaceous quartz- 

 monzonite. Until such a discovery is made, we must hold the 

 problem in abeyance, content with the fact that the Cceur d'Alene 

 intrusives, and those northeast and southwest of them, are distinctly 

 different from the average type of Idaho quartz-monzonite. 



