74 Revietrs — The Nonvegian Geological Survey — 



Up till recently the Norwegian geologists added another formation 

 to the above list, placing it above what is now classed as Silurian 

 strata, but it seems to be proved that the rocks assigned to that 

 formation are in fact masses of the older granites, gneisses, etc., 

 which have been thrust over the Cambrian and Silurian strata. 



The result of the work of the Survey recorded in the published 

 reports shows that the geological history of the district is somewhat 

 as follows : — 



ArchcBan. 



The green and white gneiss so common in the adjoining districts 

 is seldom found here in continuous masses below everything else. 



Mr, Rekstad records an occurrence some little distance eastward 

 of the snowfield Hardanger Jokel and another on the north of the 

 mountain Hallingskarvet. Patches of the old gneiss are, however, 

 common, lying in or upon the granite B in the above list. 



Mr. Bjorlykke mentions one such patch south of Skjaegge Dal 

 on the east of the Sor Fjord. It lies upon the granite, and consists 

 of greyish compact micaceous gneiss, sometimes with hornblende 

 or chlorite, with layers of hornblende schist and also of a rock like 

 saussurite gabbro. In places, too, there is gneissic granite, but the 

 hornblende rock is the most common. 



The Algonlcian or Telemarh Formation. 



Eocks whicli are assigned to this formation are developed to 

 a considerable extent along the Sor Fjord. They do not reach the 

 head of the fjord at Odde, being cut off by the granite B a little 

 north of that place. Fairly large areas of the Telemark Formation 

 have also been found near Hallingskarvet in the north of the district 

 and near the Hyls Fjord in the Suldals Fjeld. The formation 

 consists of gneiss, sometimes fine-gi"ained and passing into varieties 

 resembling quartzite, of beds of quartzite, and of layers of hornblende 

 schist. In places conglomerate occurs. 



Associated with these rocks there are on the Sor Fjord massive 

 rocks resembling saussurite gabbro in lens- or dome-shaped masses. 

 The formation is penetrated by numerous granite veins which in 

 places have been crushed into lens-shaped patches. 

 The Older Granite. 



Both, the Archaean Gneiss and the Telemark formation are, in 

 the district of which we are speaking, to a great extent cut out 

 by granite. This granite is older than the Cambrian and Silurian 

 rocks of the district, for they are never penetrated by veins from it. 

 The Telemark formation, on the contrary, is cut by granite veins 

 in all directions. 



The granite, according to Mr. Eekstad, often contains oligoclase 

 as well as orthoclase, and this is more especially the case in the 

 district north of the Hardanger Jokel. The mica is usually black, 

 light mica only occurring to a small extent. 



The granite is frequently porphyritic, and the rock is usually 

 more or less gneissic, sometimes assuming the form of augen-gneiss. 

 Pegmatite veins and also quartz veins run through it here and there, 



