1 92 1. No. II. THE STRANDFLAT AND ISOSTASY. 43 



VI. THE DEVELOPMENT OF THE NORWEGIAN 

 STRANDFLAT. 



It seems to be probable that the shore-ledges have been formed by 

 the same process as the strandfiat, and that they are in a way embryonic 

 strandfiats, that might have developed into more mature ones, if they had 

 been allowed the necessary time. 



But how may these narrow ledges develop into the broad planes of 

 the strandfiat? 



The wave action is obviously of much importance for this develop- 

 ment. While the frost is disintegrating the rock by the alternate melting 

 and freezing of ice and accumulated snow above the average high-tide level 

 — widening the ledges into broader benches and at the same time lowering 

 their floor — the waves attack the outer edge of the benches, assisted to 

 some limited extent by the frost, and in the length of time they will manage 

 to wear down this edge, even below low-tide level, and will thus get access 

 to the inner floor of the benches. There may here be plenty of débris and 

 loose stones for the surf to work with, rolling them forwards and back- 

 wards, and thus gradually wearing down the outer part of the benches, 

 and make them slope gently into the water, in the manner which may be 

 studied on a small scale on the shore-ledges of the Fornebo Peninsula 

 (cf. Fig. i8). 



In this manner the sea, headed by the sharp teeth of the frost of an 

 Arctic climate, and following with the roaring surf, may eat itself land- 

 wards and create a gradually broadening low and flat shore-plane, sloping 

 very gently seawards, and with its inner part emerged above high-tide level. 

 Landwards this plane will be bounded by a more or less vertical cliff, con- 

 tinually retreating before the attack of the frost. 



When the shore-plane attains a certain width, the waves may lose 

 their force in the shallow water over the outer submerged part of this 

 shore-plane, before they reach the emerged shore, and their kinetic energy 

 will then to a great extent l)e expended in transporting the gravel on the 

 flat sea-floor [cf. Nansen, 1904, p. 182]. But by so doing they will erode 

 the sea-floor, and will continue to do so as long as the shallowness of the 

 water prevents them from attacking the emerged shore with their ful! 



