104 
under the sandstone; it is a coarse-grained, light-reddish bio- 
tite-granite, and just as on Nugarsuk (p. 94) the lowermost 
sheets of the sandstone formation consist of arkose. From here 
up to the top of Nasanguak, the most easterly peak of llimausak, 
the mountain is built up entirely of the sandstone formation, 
and the numerous intrusive sheets in this show that no fault 
of any considerable amount of throw cuts the sandstone for- 
mation between Kangerdluak and Nasanguak. As can be seen 
from the section (Pl. VI, Fig. 2), the top of Nasanguak corre- 
sponds very closely to the upper boundary of the sandstone. 
As this mountain has a height of about 1050 meters according 
to measurements made by Dr. Sreenstrup, the total thickness 
of the sandstone formation, taking the inclination into account, 
is about 1200 meters. The original thickness of the sandstone 
has not been quite so much as this, since the intruded diabase 
sheets have considerably added to the thickness of the forma- 
tion. The lower half of the sandstone contains but few and 
thin sills, but in the upper half these are extremely numerous 
and thick: one of them has been estimated to be over 100 
meters thick, and ‘the total thickness of the sills probably 
amounts to about 300 meters, though the latter estimate is ad- 
mittedly a rough one. 
The volcanic series which covers the red sandstone, rea- 
ches an altitude of almost 1450 meters in the highest point of 
llimausak. From this we may calculate that the actual thick- 
ness of the series amounts to about 1000 meters, regard being 
taken of the inclination of the sheets towards the S.S.W. But 
since this, the uppermost formation, has undoubtedly been ex- 
posed to denudation through an enormous stretch of time, the 
original thickness of the volcanic series must have been very 
much greater, probably several thousands of meters. 
This conclusion gains in probability from the fact, that 
the porphyries in Hatten and in the highest peak of Ilimausak, 
that is, the uppermost part of the volcanic series still preserved, 
