32 
MUSEUM BULLETIN NO. 30. 
of the mass, and were otherwise variously affected by the regional 
movement described in the preceding section. The granites were 
not rendered gneissic, but were forced into intrusive relations 
with the more basic types. It is evident, therefore, that the move- 
ment occurred after a fairly complete separation of the magma 
by differentiation had taken place, after the basic types had 
become very viscous and in some places solid, and before the 
granitic differentiate had begun to l£>se its complete fluidity. 
TIME OF DIFFERENTIATION RELATIVE TO THAT OF INTRUSION. 
It has been shown that the differentiation of the Sooke 
intrusive preceded a movement that' affected the mass prior to 
ks consolidation. It remains to consider whether this movement 
was that which accompanied the intrusion of the gabbro to its 
present position, or was of later date; in other words, whether 
the differentiation went on in situ, or took place previous to 
intrusion in some underlying magma reservoir. The writer is 
of the opinion that the mass was intruded to its present position 
before differentiation took place, as the results of movement 
do not appear to have been sufficiently profound to sustain the 
hypothesis of intrusion after differentiation. In siljiport of this 
conclusion the following evidence is adduced : 
The main mass has been shown to have been liquid at the 
time of movement. It seems unlikely, if differentiation took place 
before intrusion, that a large, forward movement would have 
ended in the present spatial arrangement of acid differentiates 
on the periphery, basic ones in the centre. More likely remixing 
would have occurred. 
The formation of the separate species by differentiative pro- 
cesses which took place before movement began must have 
involved much crystallization of olivine, pyroxene, and probably 
also bytownite. It has already been shown from field evidence 
(page 31) that crystallization certainly had at least begun. It 
seems probable that any l^rge advance of the magma after 
this had occurred would have caused crushing and biecciation 
of these already-formed crystals. This effect would be most 
evident in the more basic varieties of olivine gabbro. However, 
nothing of the sort has been observed. 
