1 92 1. No. 1 1. 



THE STRA.NDFLAT AND ISOSTASY 



"fOO 



200 



Kil-omttt-L^ 



Ch iLstiama 



\0 tclovxcian. Schists conia^ning mucJi Luize^ 



^ Aicha cort Gneiss 



-1 Kolsas to Nesodd Land, from A to B in Fie;. 102. 



Tt is difficult to decide what the exact height of this plane may 

 originallv have been, because after its final planing, it has been denuded 

 by glacial erosion. Most of the land on the Fornebo Peninsula, for in- 

 stance, is lower than 20 metres, and a great deal of its area is even lower 

 than 10 metres, but this chiefly consists of fields formed of loose material. 

 The many long rockv ridges running in the direction of the strike (about 

 WSW to ENE) [cf. Werenskiold, 1911] between the flat fields are mostly 

 between 10 and 20 metres high, with their fairly flat summits slightly above 

 20 metres. They show, however, distinct traces of glacial erosion. Their 

 summits are rounded and the dykes of diabase rise above the argilaceous 

 schist with rounded, polished, and striated surfaces (cf. Fig. 17). These 

 rockv ridges have, therefore, obviouslv been somewhat lowered bv the 

 glacial erosion, but it is difficult to say exactly how much. I think, 

 however, that the general plane may be assumed to have been about 25 

 metres above present sea-level, or perhaps a few metres more. 



The sides of the rocky ridges are frequently so steep and abrupt that 

 they look like shore formations or shore cliffs somewhat modified by later 

 'dacial erosion. 



Fig. 104. Tlie plane of Fornebo Peninsula and the islands and land to the south-west, seen against the surroundung 

 higher hills. View from south to west-southwest from the top of the writer's house near Fornebo. (.April, 1922). 



