26 
of the mountains in one continuous trail to the sea, and under 
such conditions considerable areas may be found where the 
solid rock is nowhere exposed to view. On the whole, how- 
ever, the subaerial crumbling-down of the rocks is only in its 
first stages, and geological observations are only locally impeded 
by the rubbish covering. 
General character of rocks. — Both batholites are entirely 
made up of rocks which belong to the alkali series; common 
to both is also the prevalence of the nepheline-syenites. But 
in other respects the two batholites are widely different. 
The batholite of Ilimausak consists of a large number of 
individual rock-bodies. The nepheline-syenites are represented 
by lujavrites and and other relatively rare types which may be 
interpreted without difficulty to be produced by the differentiation 
of one parent magma of a peculiar composition. Besides, the 
batholite contains alkali-granite, alkali-syenite, and essexite. 
The large Igaliko batholite is of a much more uniform 
structure and composition. The principal rock is a nepheline- 
syenite related to the ordinary Foya type; it is associated with 
an olivine-bearing nepheline-syenite and with a syenite of the 
Larvik type. As the northern and eastern parts of this batholite 
have not been surveyed it is possible that future investigations 
may reveal the presence of other rocks, but the study of the 
erratics has not supported any supposition of this kind. 
Geological age of the batholites. — No direct communica- 
tions have been observed between the batholites and the vol- 
canic sheets. At the junction the rocks of the volcanic series 
show distinct effects of contact metamorphism and the batholitic 
rocks send out numerous apophyses into the surroundings whether 
these consist of Algonkian granite, of sandstone, or of volcanic 
sheets. If the dykes that traverse the batholites are excepted, 
the batholitic rocks must have been the latest igneous rocks 
of the district to consolidate among all that erosion has left to 
the present day. On the other hand the petrographic examination 
