6 



Another question of great interest is the nature of the 

 numerous dykes of basic rocks which traverse the main species 

 of rocks of this district. All earlier explorers have mentioned 

 them under the name of diabase, and Bay particularly em- 

 phasizes the fact that no basaltic dykes have been met with ^). 

 Kruuse, on the other hand, in his preliminary account of the 

 expedition -) mentions both basalt and diabase in a manner which 

 seems to indicate that he is uncertain which of the names is 

 the more correct. From what follows it will, however, be seen 

 that this is not surprising, as petrology cannot always solve 

 this problem, some of the rocks seeming to approximate in 

 their characteristics to both the above-mentioned groups. 



1 shall now briefly describe some of the most important 

 localities in which these rocks occur. 



The district of Âugmagsalik. 



The greater number of the specimens which I have had 

 for examination come from this district. The most complete 

 series is from a place called »the grav el- pit» (Grusgraven)^) 

 situated at about lat. 66° 5' N. and long. 35° 35' W., some 55 

 miles NE. of the trading-station. According to Kruuse it is 

 a valley surrounded by lofty gneiss mountains and partly barred 

 by a greenstone dyke. Among the specimens collected at this 

 place, of which some are loose fragments, which, however, can 

 hardly have been brought there from any great distance, the 

 following are noteworthy: — a hght-coloured medium-grained 



M Geogiaphisk Tidsskrift Bd. 15, p. 64. 



') I. c. p. 177. Лог did i come across any greenstone dykes in the im- 

 mediate neighbourhood of the colony itself, the nearest 1 observed being 

 about 16 miles oil". С Kruuse. 



') Properly speaking, this lie.« outside the di.strict of Anginatjsalik, which 

 only extends to .Sermiligak, but it is mentioned here in this connection 

 as being the northernmosi point whence I was able to brine a fairly rich 

 collection. (.;. Kruuse. 



