366 



R. A. DALY THE OKANAGAN COMPOSITE BATHOLITH 



granites alongside. We have seen, on the contrary, that the Similkameen 

 granite on the east is notably free from such records of orogenic turmoil, 

 while the shear zones of the Eemmel batholith on the west most probably 

 antedate the Cathedral granite intrusion. The very scale of these great 

 bodies is suggestive of bodily replacement ; it is hard to visualize an earth's 

 crust which would so part as to permit of the laccolithic or chonolithic 

 injection of a mass as great as a batholith. 



The general absence of bedded rocks into which any one of the batho- 

 liths was irrupted means that some of the usual criteria of replacement 

 can not be applied. It is therefore a matter of special importance that a 



Figure 9. — Plunging Contact Surface between intrusive Qranodiorite and Cretaceous 



Argillites and Sandstones. 



Drawn from a photograph of the west end of the Castle Peak stock. View looks 

 south. Contact shown by heavy line in middle of view ; the point "B" in figure 7 is at 

 the upper end of this line. Intrusive granodiorite on left, argillites and sandstone on 

 right. The vertical distance between the two ends of the contact line as drawn is 1,500 

 feet. Castle peak on the left. 



small Tertiary stock, such as Castle peak, a satellite of the composite 

 batholith itself, gives unequivocal proof of the doctrine of batholitbic re- 

 placement. 



The Castle Peak stock, which covers 10 square miles in area, is located 

 on the divide between the Pasayten and Skagit rivers, in the rugged 

 crest of the Hozoineen division of the Cascade range. The peak is the 

 highest of a group of noble mountains lying wholly or in part within this 

 small plutonic area. This igneous body is composed of typical granodio- 

 rite with a strong basified contact zone of hornblende-biotite quartz dio- 

 rite. The area and ground plan of the stock are shown in figure 7. The 



