26 
MUSEUM BULLETIN NO. 2. 
reaching its final resting place also must have affected the 
uprising magma. Examples of such action are described by 
Harvie. 1 Inclusions in dykes around Mount Royal at Mon- 
treal, show that these inclusions have risen at least 2,050 feet 
from their point of origin and perhaps a greater distance, for in 
the same dyke other zenoliths have sunk 2,000 feet from their 
point of origin. These zenoliths, which are great in number, 
often show evidences of solution by the enclosing igneous 
material. In the East Kootenay district one dyke was found 
in connexion with the Purcell Sills which was crowded with 
small fragments of crystalline limestone which is not represented 
in the Aldridge formation as far as known. Thus, the evidence 
of some contamination of the magma by material through 
which it passed is strong and if the acid material of the com- 
posite sills is indeed of extraneous origin, it would be perhaps 
more justifiable to assume that it was absorbed by the uprising 
magma before it entered the Purcell Series. 
Another field fact of prime importance is that in those sills 
whose upper contacts were so exposed as to be traceable for long 
distances, the contact between the sediments and the sill was 
remarkably uniform and not irregular as might be expected if 
stoping had been very active. 
A modification of this theory was discussed with Dr. R. A. 
Daly. It is as follows: assimilation of the blocks of sediment 
took place in the lower larger sills; the syntectics thus formed 
were drawn off in some manner and injected into a higher 
horizon where they differentiated under the action of gravity. 
The following field facts do not support this hypothesis: — 
(1) Many sections containing thick sills contain no 
granite (micropegmatite) in any of the sills. 
(2) The upper contacts of the larger sills in sections 
which do contain granite (micropegmatite), where examined, 
show a smooth upper contact. If stoping took place to 
such a degree as to form large quantities of granite 
(micropegmatite), the upper contact would be irregular 
showing the effects of stoped off blocks. 
’Harvie, R., Trans. Roy. Soc. of Can. 3rd series, vol. 3, 1909-10, p. 277. 
