432 DEPARTMENT OF THE INTERIOR 



2 GEORGE V., A. 1912 



the old mountain substance was removed during the successive batholithic 

 intrusions. Thus the sedimentary crust has also been attacked from beneath; 

 its integrity has been destroyed through the displacing or replacing of sediments 

 by igneous magma. In bringing about this gigantic result all the batholiths 

 have acted together. Though they are of very different ages, their energies have 

 been devoted to a common work. Their effects are so integrated that in causing 

 the nearly complete disappearance of the ancient strata they have imitated on a 

 larger scale what occurs with any homogeneous batholith. From this point of 

 view the Boundary belt, stretching from the eastern contact of the Osoyoos 

 batholith to the western contact of the Kemmel batholith, forms a small segment 

 •of one composite batholith somewhat broader than the Okanagan range. To 

 emphasize this primary fact, the whole plutonic mass has been called ' The 

 Okanagan Composite Batholith.' 



Sedimentary Bocks and Associated Basic Volcanics. 



Within the five-mile belt the only rocks of sedimentary origin are those 

 which, with much probability, may be regarded as part of the Anarchist series 

 already described. The largest area is found in Kruger-mountain plateau, 

 where the dominant types in the country-rock of the plutonic masses are cleaved, 

 micaceous quartzite and still more abundant sheared greenstone or amphibolite. 

 The description of these rocks would be largely a repetition of that given for 

 the Anarchist series as developed to the eastward of Osoyoos lake. The chief 

 differences consist in the lower proportion of true phyllite in Kruger mountain 

 .and in the somewhat higher degree of crystallinity (metamorphism) shown in 

 the western mass. Furthermore, no limestone has been found in Kruger moun- 

 tain. These differences are, however, not of the kind to forbid direct correlation 

 -of the two terranes. The proximity of the two and the very positive resemblances 

 of the rocks and associations on the two sides of the lake make the correlation 

 probable in high measure. The greenstone?, and amphibolitic rocks carry thin 

 interbeds of a once-argillaceous type, now phyllite, as well as thicker bands of 

 the dominant quartzite. One thin section seems to prove that part of the green- 

 stones are pyroclastic and basaltic or andesitic in original composition. These 

 igneous rocks are almost certainly contemporaneous with the silicious sedi- 

 ments. The quartzite was occasionally seen to be thinly banded and cherty, 

 recalling some of the normal types in Dawson's Cache Creek (Carboniferous) 

 series. 



The quartzites of the Chopaka roof-pendant (inclosed in the Similkameen 

 batholith) have been examined microscopically. They show the usual characters 

 of a metamorphosed quartzite, being rich in shreds and minute foils of a green 

 biotitic mica; feldspar was not discoverable in either of two thin sections. The 

 amphibolites of the Horseshoe and Snowy pendants, like those of the Kruger- 

 mountain mass, are of quite usual microscopic characters, indicating the deriva- 

 tion of these rocks from basic volcanics. Their full description would be 

 tedious and unnecessary. 



