Basic complex 343 



nodules from li/ 2 to 2 inches in diameter. These nodules are thickly 

 and quite uniformly scattered through a coarse matrix of green horn^ 

 blende. The dike is interesting on account of its peculiar structure, but 

 is of little importance as a member of the complex as a whole; no other 

 dike of the kind was found. 



As there is no discoverable system in the differentiation of the earliest 

 intrusive members, varying as they do most capriciously from ledge to 

 ledge, so there is no discoverable system in the trends or occurrence of the 

 countless later injections of the gabbros. The complication has been 

 still further increased by the intrusion of thousands of narrow and broader 

 dikes of granite. Much of the granite is apophysal or aplitic from the 

 Eemmel batholith ; some of it is apophysal from the magma supplying 

 the Park granite stock, while many dikes of acid pegmatite locally traverse 

 the whole mass. The complication was finally made perfect through the 

 enormous crushing which the Basic complex underwent, both during the 

 intrusion of the granites and during the orogenic revolution when the 

 Eemmel granodiorite itself was sheared into banded gneisses. 



In the shearing of the Basic complex its material was metamorphosed 

 and, in part, it migrated. The mode of migration is believed to be that 

 which will be briefly discussed in connection with the petrographic de- 

 scriptions of the crushed Osoyoos and Eemmel batholiths. The meta- 

 morphism has developed many schistose phases, among which hornblende- 

 biotite-diorite gneiss (specific gravity, 2.766 to 2.863) and well foliated 

 hornblendite are common. 



As a result of this long and varied history, scarcely any two ledges 

 within the area of the Complex accord in composition. The constitution 

 of what appears to be the commonest phase of the Complex, the augite- 

 hornblende gabbro, and the peculiar fawn color of its feldspar furnish a 

 probable correlation of part of the whole mass with the Ashnola gabbro. 

 There is no certainty of similar correlation with the basic rocks of mount 

 Chopaka. 



OSOYOOS GRANODIORITE BATHOLITH 



Macroscopic and microscopic characteristics. — The original rock of the 

 Osoyoos batholith is a typical medium to coarse grained granodiorite. 

 The color is the familiar light gray characteristic of monzonites, grano- 

 diorites, and some other granular rocks rich in plagioclase. In the like- 

 wise fresh though somewhat metamorphosed phases the rock assumes a 

 light greenish gray tint due to the dissemination of metamorphic biotite 

 or to the abundant development of epidote. All phases weather light 

 brownish gray. The essential constitutents are deep green hornblende, 



