I92I. No. TI. THF. STRAXDFLAT AND ISOSTASY. 69 



the projecting spurs on the sides of a valley in a manner similar to that 

 suggested by Ahlmann [1919, p. ~2), Fig. 35]. The very nearly uniform 

 height of the points must have been determined by the sea-level at the 

 time of their formation, while the erosion of the glaciers that filled th^ 

 Sogne Fjord could not be fletermined by the level of the sea to any 

 similar extent. 



Without considering whether spurs may be eroded by glaciers in the 

 manner suggested by Ahlmann, the distinct incisions frequently formed 

 in the mountain slopes by the flat platforms of the rocky points along the 

 sides of Sogne Fjord also prove that they cannot have been originated 

 m such a manner. 



There seems to me to be no other feasible explanation of the genetic 

 origin of these flat rocky points and benches along the sides of Sogne 

 Fjord, as well as Hardanger Fjord, but that they have been formed by 

 shore erosion, chiefly by frost, and that they are formations identical with 

 the Strandfiat of the outer coast. The fact that this strandfiat in the fjords 

 chiefly occurs on the rocky points and headlands, and much less along the 

 shores between the points, is what might be expected, considering that 

 the shore erosion by frost has a much greater surface for attack along the 

 sides of a headland, than along the straight coast. 



Summary. We may summarize our researches in Sogne Fjord as 

 follows: numerous indications of a strandfiat occur along both sides of 

 Sogne Fjord and in its side branches, chiefly on most of the points and 

 promontories. The altitude above the sea of the horizontal level of this 

 strandfiat varies somewdiat in the different regions of the fjord, it being 

 about 10 metres in the inner part in Sogndal Fjord, Norum Fjord, and 

 Leikanger, about 12 metres in Tjugum and Balestrand, and about 16 or 17 

 metres in the outer part of Sogne Fjord from Tangen and Hoiang Fjord 

 to its mouth at Rutletangene. 



A higher level of the strandfiat, about 25 metres above the sea, was 

 observed in Tjugum (on \>garnes and at Tjugum church), in Balestrand, 

 on Vangsnes, at Matsnes, and perhaps on Rutletangene. This is the ap- 

 proximate height of the inner boundary line of the strandfiat at Matsnes, 

 where it forms a distinct incision in the mountain slope. 



The Strandflat north and south of the Mouth of Sogne Fjord. 



North of the mouth of Sogne Fjord a strandflat was observed on the 

 northern peninsula of huicr Siilcn, and especially well developed on the 

 islands Buskoi, Færoi, and Drevoi to the west. The strandflat is very 

 conspicuous on Sakrisoi and Luten Island to the northeast of Inner Sulen, 

 and also on the mainland at Ski venes, east of Sakrisoi (see Fig. 21). The 

 rock is chiefly phyllitic schists in the whole of this region. 



