I92I. Xo. II. THE STRAXDFLAT AND ISOSTASV. 93 





Fig. 77. Strandflat north of Haugesund. lAug. 30, 191 1). 



(Fig. 79) but, as mentioned above, a good many hills rise more or less 

 abruptly above its plane. The geological structure differs much on the 

 two sides of the sound, the rocks being gabbro on Karmoi and chlorite 

 schists on the mainland; but there is no appreciable difference in the 

 appearance or height of the strandflat. 



A well marked strandflat. with a height approaching 30 metres, and 

 forming a sharply defined incision in the mountain slope extends along 

 the western and southern side of Eastern Baku island consisting partly 

 of phyllite partly of Archæan rocks (Figs. 81 and 82 K 



On the southern side of the island another level was noticed at about 

 double that height or a little more (Fig. 82). 



On the southern part of Western Bokn island (chiefly Archæan rocks 

 and some phyllite), there is also a distinct strandflat. 



The Stavanger Region. 



The northwestern end of Rennesoi. north of Stavanger, forms a very 

 flat and low strandflat (cut in granite), with a height of less than 20 

 metres (Fig. St,). 



Ahlmann in his attempt to prove that the strandflat has not been 

 formed by marine denudation, points out that the occurrence of the strand- 

 flat or rocky bench with a steep cliff behind it, on the southern side of 

 Rennesoi, coincides with the tectonic difference in the geological structure 

 of the island where igneous rocks, forming the cliff, rest on a base of 

 weaker sedimentary rock (phyllite), forming the strandflat. He thinks 

 that in such a case the formation of the bench "can be well explained as 

 a result of subaërial and glacial erosion, but not by marine abrasion". 

 But what is the explanation in the manv thousands of other cases of 

 similar shore-benches or strandflat formations where there is no such 

 tectonic difference? And why have the horizontal strandflat and the 

 shore-benches so very similar heights, or to a great extent practically 

 identical heights, in the different regions so widely separated, although 

 the rocks may differ much in their power of resistance to erosion? It 

 seems that Ahlmann, in his anxiety not to admit the effect of the marine 

 abrasion, has been compelled to seek for different explanations of the 

 same formations in the different cases. 



