22 
from the Gulf of St. Lawrence to Scoresby Sound, and it will 
thus be seen that the geological conditions of the sedimentary 
areas which lie nearest to South Greenland strongly support the 
view that the only geological periods to which the Igaliko 
Sandstone can be referred with some degree of probability are 
the Devonian and the Triassic. 
On the other hand the following considerations will show 
that the assumption of a Devonian age is much more likely 
than that of a Triassic age. (1) The Igaliko Sandstone bears a 
much closer resemblance to the Devonian series of the district 
north of Scoresby Sound than it does to the Triassic series of 
this district. (2) The enormous amount of the denudation to 
which the plateau of South Greenland has been subjected since 
the formation of the Igaliko Sandstone and the volcanic series 
strongly suggest that the geological age of these rocks must be 
much older than the Mesozoic. The original thickness of the 
sandstone and the volcanic sheets must have amounted to 
several kilometers, nevertheless they have been entirely removed 
from thousands of square kilometers and have escaped total 
destruction only within a narrowly limited and deeply sunken 
area. A still more suggestive testimony of the great amount 
of the denudation lies in the fact that the nepheline-syenites 
and the other true abyssal rocks which are later than the sand- 
stone are exposed to view over extensive areas of South Green- 
land (compare map, Plate I). 
It will appear from the above discussion that a number 
of facts, the most important of which are due to the investiga- 
tions of recent years in East Greenland, tell strongly in favour 
of the view, first expressed by GiesecgE, that the Igaliko Sand- 
stone is of Devonian age. 
NEWER ABYSSAL ROCKS. 
The abyssal rocks of South Greenland which are later than 
the Igaliko sandstone are granites, syenites, nepheline-syenites, 
