326 
(2) The syenite may be a later intrusion forced up between 
the nepheline-syenite and the encasing rocks. The syenite on 
this assumption would be a kind of dyke. 
(3) The syenite may have been intruded prior to the nephe- 
line-syenite. 
In order to settle the question it is necessary to discuss the 
contact relations. At the outer margin, where the syenite borders 
upon Algonkian granite and sandstone, the contact features are 
of the well known kind which characterize the junction of a 
batholite with country rock. They are the reduced size of grains, 
enclosed fragments of the wall rock, numerous apophyses, and 
contact metamorphism of the wall rock, which have been de- 
scribed (pp. 51, 59, 103). Away from the margin of the ba- 
tholite, at the junction of ithe syenite with the nepheline-syenite, 
the contact relations are entirely different. There, in the exposed 
sections, the junction generally appears as a definite line, and 
both rocks are coarse-grained to the very contact. There is 
no contact metamorphism, and no apophyses have been ob- 
served. At Iviangusat, where this junction is excellently exposed, 
the size of grains of the nepheline-syenite actually increases 
near the contact, and fragments of the syenite are enclosed 
within the nepheline-syenite. The latter, moreover, is cut by 
numerous veins of extremely coarse-grained pegmatite, and 
the veins are parallel to the contact plane (p. 48), and hence 
the nepheline-syenite must have consolidated later than the 
syenite, but not so much later than that the syenite had time 
to cool down. 
Another circumstance of great interest is the peculiar be- 
haviour of the stratification of the nepheline-syenite near the 
contact. The contact plane, as a rule, is almost vertical and 
the stratification nearly horizontal. Moreover, on approaching 
the contact the stratification does not change its direction, but 
gradually fading away becomes indistinct, until the nepheline- 
syenite nearest to the junction does not present any sheeted 
