Karl Pettersen — Geology of N. Nonuay. 387 



Porsanger and the greater part of the high and wild peninsula which 

 extends from Langfjord and Alteidet westward in the direction of 

 Loppen. 



In the inland area of the district (Amt) of Tromso the primitive 

 rock appears in several places, but always in narrower stripes. 



The masses of the strata are formed of grey and red gneiss, horn- 

 blende gneiss and hornblende slate, hard micaceous schist, mild 

 shining mica-slate and quartzitic slate. Also layers of chloritic 

 slate may be found alternating with the same. The strike goes 

 usually in the direction of north and south, with deviations sometimes 

 on the one side and sometimes on the other. The dip is often con- 

 siderable, sometimes even vertical, but in other places it is more 

 nearly horizontal. The dip is to the east or to- the west, or sinuous. 

 In some places where the dip is great, such strong sinuosities may 

 repeatedly occur in a longitudinal extent of some few hundred metres. 



From the regular north and south direction of the strike there 

 may occur in some places strong local deviations, even changing to 

 an east and westerly direction, in large connected tracts. 



With this widely extended gneiss section there are connected 

 large masses of granite, gneissoid granite and granitoid gneiss 

 forming the chief part of the great Island-group of the coast-tract. 

 The connexion between the purer gneiss and the granitic rock is 

 such that, in spite of the strong petrographic divergence between the 

 extreme links, there appears to be every probability that gneiss and 

 granite with reference to their ■ common origin and age belong to 

 one and the same main group. 



Gneiss is on the whole poor in accessory minerals ; but in 

 micaceous gneiss, red garnets are often found in great abundance. 

 Also blue disthene is found in one place in the gneiss. Graphite 

 often appears in it in the shape of leaves or lumps. In the grey 

 gneiss we find Fahlbands with a sprinkling of Pyrites. 



For a more particular estimate of the thickness of the primitive 

 rock occurring here, the necessary data are wanting. That the 

 thickness is however considerable, appears from what may be ob- 

 served in the occurrence of this rock in the region of Eibbeneso in 

 the parish of Karlso. 



The so-called primitive rock here treated of is probably that 

 which may be most likened to the Laurentian formation observed in 

 Canada. This formation is here supposed to be divisible into an 

 older and a younger section. 



II. — The Tromso mica-slate group occurs in the coast-tract Island- 

 group in several places over a greater or less area. For instance, in 

 Soro, Loppen, Vanna, Eingvatso, Kvalo, Senjeno, Hindo, while in 

 the islands of Lofoten and Yesteraalen it is almost entirely sup- 

 pressed. But it forms especially a very prominent link of structure 

 in the mainland tract proper of the Tromso Amt. 



The mica-slate group is formed of mica-slate, quartzitic slate, and 

 sometimes also hornblende-slate; but the strata of greyish- white 

 coarse granular limestone are most frequently occurring and charac- 

 teristic of the group. 



