239 
To the east and north it abuts on the nepheline-syenite, to 
the west on the rocks of an older origin (vide map, PI. IV). 
The rock is very rapidly decaying, and consequently it has 
given rise to the formation of plains more or less level and 
covered with rubbish which contrast markedly with the more or 
less steep slopes of the abutting nepheline-syenite (Pl. XVII). 
As a rule these rubbish plains lack vegetation, but a certain 
break in the uniformity is produced by the presence of small 
rocks projecting through the rubbish on account of their greater 
power of resisting erosion. The augite-syenite in Korok’s coast 
rocks forms an exception to this. The rock is here altogether 
fresn rd compact, no doubt because the glacial erosion in the 
fjord has been so intense that the hardest parts of the rock 
only have been preserved. 
Petrography. 
Macroscopic appearance. — In its outer appearance the 
augite-syenite of the Igaliko batholite shows a considerable 
likeness to that of the Ilimausak batholite, but still more striking 
is the likeness to the familiar larvikite from southern Norway. 
As will be seen from the following this likeness also extends 
to their microscopic characters and chemical composition. In 
its freshest state the rock is of a dark gray colour, but usu- 
ally it is of a somewhat lighter gray or brownish-gray, and on 
the surface it can sometimes be reddish-gray. The structure is 
coarse-grained; an imperfect parallel arrangement of the oblong 
felspar crystals is found in some cases. Porphyric varieties 
have especially been found in the western part of the area 
near the junction of the sandstone. The main constituent of 
the rock is a gray, semi-transparent felspar which becomes 
whitish by weathering and very often shows a beautiful blue 
schiller. The crystallographic form of the felspar is badly 
developed, still, on fresh surfaces of fracture the rock exhibits 
felspar sections which evidently tend towards stout rectangular 
