— 
Me) 
west; on the whole it is parallel to the direction of the part- 
ings in both rocks. The thickness of the sodalite-foyaite at 
this place amounts to about 200 meters. To the north and 
west the thickness decreases; two and a half kilometers west 
of North Siorarsuit it is reduced to some few meters. 
In the upper parts the sodalite-foyaite gradually becomes 
poorer in sodalite and passes into a foyaite, which contains 
olivine and is of the same composition as the foyaite south of 
Tunugdliarfik (p. 69). As the transition is very slow I am un- 
able to give the exact thickness of the olivine-bearing foyaite; 
probably it does not exceed ten meters. 
Transition from foyaite to arfvedsonite-granite. — A con- 
siderable body of arfvedsonite-granite rests upon the foyaite 
(see Pl. VI, Fig, 1 and Map Pl. Ш), and the two rocks are con- 
nected by a gradual transition. This interesting transition from 
a nepheline-syenite to an alkali-granite was more closely 
studied in the mountain slope facing the east, just over the 
head of the alluvial fan of North Siorarsuit. Here the following 
series of coarse-grained rocks was found (in descending order): 
Arfvedsonite-granite 
Quartz-syenite, red (ca. 16 meters) 
Pulaskite, red (ca. 4 meters) 
Pulaskite, white (ca. 5 meters) 
Pulaskite, white, with pegmatite (ca. I meter) 
Foyaite 
These rocks lie as almost horizontal strata above one an- 
other without any sharply defined contact between them. In- 
specting the cliff from below upwards we observe, at an altitude 
of about 370 meters, that the foyaite passes into a coarse- 
grained pulaskite without showing any variation in the size of 
grain. The pulaskite is of quite the same composition as the 
pulaskite south of Tunugdliarfik (p. 69). The lowest bed of 
pulaskite, which is about a meter thick, contains grains of a 
