319 
The essexite occupies a small area around the Narsak settle- 
ment. The original form of the whole essexite body cannot 
be indicated, as the rock on one side borders upon the sea 
while on the other it is in contact with the younger syenite. 
The syenite apparently has stoped away a portion of the 
essexite, and the structural planes of this latter rock are cut 
off by syenite which contains fragments of essexite. 
The essexite was probably intruded in a different way from 
the other abyssal rocks of the complex. This is indicated (1) by 
the presence of very wide dykes of coarse-grained essexite — 
which increase slightly in width towards Е. М. Е. — (eg. on the 
isle of Tugtutok (west of Narsak), and in the case of one large 
dyke of a similar rock at Kangerdluak (N. E. of Narsak)), and 
(2) by the frequent occurrence of flow structures, which are 
more or less vertical even within the main body of the essex- 
ite. The strike of this vertical structure was noted during the 
field work at one place only (namely at Panernak) where it runs 
from Е. N. Е. to W. $. W., and parallel to the ordinary direction 
of dykes over the entire district. These circumstances seem 
to indicate that the essexite of Narsak cannot be considered 
as an ordinary ‘batholitic’ rock body but may, perhaps, re- 
present the confluence of two or more converging dykes, 
whose westward continuation is concealed under the sea, and 
whose eastern continuation has been stoped away by the syenitic 
In this part of the complex the syenite is the dominant 
rock. It has a wide distribution in the country north of Nar- 
sak where it has a reddish colour, and as it often contains 
a little quartz it has been called Nordmarkite. South of Tu- 
nugdliarfik Fjord the syenite most often is a gray and olivine 
bearing augite-syenite. The difference in chemical composition 
between the two varieties is not very great (compare analyses 
16 and 17) and transitional forms are observed. Geologically both 
syenite masses may perhaps be regarded as one unit. 
