63 
rectangular sections. The appearance of the rock thus recalls 
that of certain varieties of syenite (nordmarkite) on the shore 
of Tunugdliarfik lying directly opposite. 
The syenite shows as usual a fine-grained border-modifica- 
tion at the junction with the sandstone and the diabase, and is 
thus distinctly more recent than these; on the other hand, the 
coarse-grained syenite extends right out to the contact towards 
the nepheline-syenites. 
The nepheline-syenites appear close to the north-east of 
S. Siorarsuit and from there extend further in an easterly and 
south-easterly direction. The cliffs of the coast consist of 
naujaite traversed by lujavrite veins in the same manner as 
above described (p. 37). Higher up the lujavrite veins are 
wanting but the naujaite continues until about 400 meters above 
the sea; it is here covered by the sodalite-foyaite and a little 
more than 100 meters higher up, this in turn is overlain by a 
white svenite poor in nepheline, which forms the uppermost 
part of the plateau north-east of Nunasarnausak. The rocks 
last mentioned and their mutual relations will be dealt with in 
more detail in the next section (Environs of Naujakasik and 
Tupersuatsiak). 
The ilvaite locality at S. Siorarsuit. — The igneous rocks 
of S. Siorarsuit have been described above as naujaite, lujavrite 
and augite-syenite, but over an area of perhaps a quarter of a 
square kilometer their appearance is very different from the 
ordinary, their original mineral constituents being partially or 
wholly replaced by new. Within this area, which stretches from 
S. Siorarsuit a little over half a kilometer along the coast to- 
wards the east, the rocks have been intensely altered by chemi- 
cal processes, which without doubt must be referred to pneu- 
matolytical action. Where these processes have only been at 
work to a small extent, the original structure of the rock has 
been preserved, but at many places the alteration processes 
have effected changes of a more radical kind, and in such cases 
