Other subordinate beds, of less common occurrence, consist of 
a red-and-white, jasper-like chert. The microscopic examination 
of a specimen of the latter kind, found by Dr. Sterxstrup at 
Igaliko, has revealed the presence of numerous sponge-spicules. 
Beds of conglomerate, from half a meter to two meters in 
thickness, are very common in the Igaliko Sandstone. All the 
pebbles are well rolled; most of them are small but in some 
beds they range up to two or three decimeters in diameter, 
and occasionally thoroughly rounded stones half a meter in length 
have been observed. Almost all of them consist of a red sand- 
stone of the same appearance as that of the underlying sand- 
stone beds; granite-pebbles have been found in a few cases 
while pebbles of diabase are very rare. 
Where the Igaliko Sandstone comes into contact with in- 
trusive masses of fairly large dimensions it is intensely meta- 
morphosed. The red-coloured sandstone is altered to a white, 
sometimes greenish or black, indurated quartzite-like rock, and 
the shaly beds are transformed into a dark-coloured hornfels 
rich in biotite. 
Volcanic sheets. — The Igaliko Sandstone is conformably 
overlain by a volcanic formation consisting of a series of lava- 
flows and sills which, according to their outer appearance may 
be designated as diabases, porphyrites, and porphyries. Inter- 
calated beds of indurated volcanic tuffs are found, but appear 
to be very subordinate. The petrographical examination has 
proved that the volcanic rocks belong to the alkali series and 
should be classed as trachydolerites and alkali-trachytes. 
The volcanic rocks are found almost exclusively in the 
vicinity of the Ilimausak batholite described below, and they 
form a roof over this batholite. Without exception they have 
been highly influenced by contact-metamorphism. No doubt 
the non-metamorphosed parts of the volcanic sheets were more 
liable to decay and have therefore been entirely removed by 
erosion. 
XXXVIII. 2 
