342 R. A. DALY THE OKANAGAN COMPOSITE BATHOLITH 



profoundly affected the more acid rock, there is far less crushing action 

 manifest in the gabbro than in the granodiorite. Gneissic structures were 

 indeed sometimes seen in the ledges, but banding was never discovered 

 and the granulation is seldom comparable to that of the Remmel. It is, 

 moreover, suspected that some of the gneissic arrangement of minerals in 

 the gabbro is due to fluidal alignment of its tabular feldspars in the orig- 

 inal magmatic period. For some unknown reason the gabbro has resisted 

 crushing and shearing better than the granodiorite. 



BASIC COMPLEX 



Petrographically and structurally, the Basic complex is perhaps the 

 most steadily variable plutonic masses in the entire boundary section from 

 the Great plains to the Pacific. It covers an area stretching from Ash- 

 nola river westward over Park Mountain ridge, a distance of 5 miles. The 

 extreme north-and-south diameter is about 3 miles, and the total area is 

 nearly 7 square miles. The Eemmel granodiorite once completely sur- 

 rounded the complex, which, as above noted, is in pendant relation to the 

 batholith. The pre-Remmel extent of the complex was greater than the 

 area now exposed ; how much of it was destroyed during the Remmel in- 

 trusion it is impossible to say. The part thus remnant was still further 

 diminished during the intrusion of the Park granite, which now, as illus- 

 trated on full 3 miles of contact line, projects strongly into the body of 

 the complex. A large block of the latter formation, measuring about 400 

 yards in length by 200 yards in width, was found within the Park granite 

 mass itself ; it may represent a roof pendant in the stock, and thus a small 

 analogue to the larger basic body in its relation to the Remmel batholith. 



The Basic complex is made up of a remarkable assemblage of basic plu- 

 tonic rocks of at least three different periods of intrusion. The oldest 

 types are coarse grained. They include highly irregular bodies of horn- 

 blendite, which in the field is often seen to be transitional into a labra- 

 dorite-bearing hornblende-augite peridotite; this in its turn merges into 

 hornblende-augite gabbro. All of these rocks are believed to be of con- 

 temporary origin. Their occurrence is so sporadic that it is difficult to 

 say how much of the whole basic area they really cover — possibly one- 

 quarter of it by rough estimate. These rocks are cut by many large dikes 

 and more irregular masses of hornblende-gabbro, augite-hornblende gab- 

 bro, and hornblende-biotite quartz gabbro. Such types are of medium to 

 coarse grain. Their specific gravity varies from 2.873 to 2.986. 



One 40-foot dike cutting the younger gabbros singles itself out as a 

 unique petrographic type. It is an amphibole peridotite in which the 

 olivine occurs in large, potato-shaped or ellipsoidal, coarse grained 



