85 
the great differences in the heights and the necessity of return- 
ing each evening to the tent on the shore of the fjord meant 
a considerable loss of time, and as but few days were available 
for the investigation of this region in 1900, the work was of 
a more cursory nature than in the case of the regions hitherto 
dealt with. When the author visited the district in 1908 at the 
end of July, the moutains were covered with snow from 500 
meters upwards and no geological investigations were possible. 
ABYSSAL ROCKS OF ILIMAUSAK. 
The nepheline-syenites are mainly represented by naujaite 
and lujavrite in the upper parts of Ilimausak. The sheets rise 
rather rapidly from North Siorarsuit towards the west and north 
and are exposed to view over a ring-shaped area round about 
the arfvedsonite-granite. This ring of nepheline-syenite is nar- 
rowest close to the south of Mount Steenstrup, where the 
nepheline-syenites are partially covered by the Narsak Glacier. 
Ascending from North Siorarsuit towards the west and fol- 
lowing the western part of the nepheline-syenite belt, we reach 
the watershed above Igdlunguak at a little below 600 meters; 
close to the west of the watershed lies a lake (Tasek), whose 
surface is about 500 meters above the sea. The larger, eastern 
part of the lake is surrounded by naujaite with very few veins 
of lujavrite. To the west the naujaite borders upon almost 
horizontal sheets of porphyrite, which are older than the nau- 
jaite; but the junction is not well exposed, the plateau being 
to some extent covered with morainic material. At one place 
near the boundary a white augite-syenite is observed, probably 
a continuation of the augite-syenite zone between Nunasarnausak 
and South Siorarsuit. North-west of the lake, at a height of 
only 520 meters, we come across another watershed, from which 
we have a view down into a broad valley which extends from 
the Narsak Glacier towards the W.S. W. Naujaite forms a great 
part of the mountain slope on the west side of the valley, but 
