MICROPEGMATITE IN PURCELL SILLS. 
25 
so excessive as to be almost improbable, especially when 
considered in the light of countless observations all tending to 
show the low thermal energy of sheet-like bodies of basic rocks. 
Apparently Daly’s argument also fails in another way, since in 
East Kootenay it has been found, as illustrated by many cases, 
that the thickness of the granite (micropegmatite) in any sill 
bears no relation to the thickness of the sill itself, which would be 
absolutely necessary under the assimilation-differentiation hypo- 
thesis. 
The strong emphasis placed by Daly on the chemical similarity 
between the granite (micropegmatite) and the enclosing quartz- 
ites (as shown by the following analyses), loses much of its force 
when critically examined. 
1. 
2. 
SiOs 
76-90 
0-35 
11-25 
0-69 
3-04 
0 02 
101 
0-88 
72-05 
0-63 
11-88 
0-83 
4-87 
0-12 
0-85 
2-10 
TiOz 
AI 263 
Fe*Oj * * 
FeO 
MnO 
MgO 
CaO 
SrO 
NasO - 
3-28 
1-36 
0-20 
1-20 
tr. 
015 
2-20 
2-66 
0-10 
1-21 
0-37 
0-09 
K 26 
H 2 0— 
H 2 O+ 
C0 2 . . 
p20l 
S.G 
100-33 
2-680 
99-96 
2-790 
1. Represents the analysis of a type specimen of Kitchener (Aldridge) quartzite; 
2 is the average analysis of acid zone, Moyie sill. 
The rocks into which the sills are intruded are not all quartzites 
as might be concluded from Daly’s description. Half of the 
series are very slaty and argillitic, analyses of which are not 
available, and, the rocks which he holds to have been assimilated, 
may just as well be conceived to be dominately argillitic as 
quartzitic. The rocks through which the magma passed before 
