I92I. No. Il- THE STRANDFLAT AND ISOSTASY I35 



bv the Norwegian Geographical Survey i "'Xorges Geografiske Opmåling";. 

 The black areas on the land have heights lower than 30 metres (100 feet) 

 above sea-level, the dark hatching on the land indicates areas with heights 

 between 30 and 50 metres above sea-level, and the light hatching in the 

 sea indicate submerged plateaus with depths less than 25 metres below 

 sea-level. The black spots in the sea indicate islets and skerries rising 

 above sea-level, and the small crosses mark sunken rocks and shoals. 

 Isobaths are drawn for every 50 metres below sea-level. The figures on 

 the land and in the sea give the heights and depths in metres. 



}klaps of the same coast have been published by J. H. L. ^ ogt [1900, 

 pp. 36 — 2)7 g^i"^!"? the emerged and submerged strandfiat in less detail, 

 and by J. Rekstad [1915] gi'^'irife the isobaths of the sea. 



Our map Fig. 113 shows that the greatest part of the emerged strand- 

 flat has heights less than 30 metres, and the areas with heights between 

 30 and 50 metres are comparatively so very small that it may seem doubt- 

 ful whether they can be considered as actually belonging to the strandfiat, 

 the base of the steeply and abruptly ascending hill-sides being as a rule 

 lower than 30 metres above sea-level. 



It has already been (p. 127) pointed out that the general level of 

 the emerged strandfiat is on the whole lower in this northern region than 

 along the coast of Norway further south. I have not had an opportunity 

 of actually measuring the height of the strandfiat along the coast of 

 Helgeland, but as far as I can make out from the maps, from my photo- 

 graps, and from the most accurate measurements made by previous in- 

 vestigators, especially Sahlstrom, the general level of the emerged strand- 

 flat of Helgeland seems to be between 10 and 20 metres above sea-level, 

 and in some places even somewhat lower [cf. Sahlstrom, 1914 . 



I shall return to this subject later, but wish first to draw attention 

 to another striking feature in the formation of the strandfiat of this region 

 brought out very clearly by our map. It is the wide extent of the very 

 flat submerged plateaus of the strandfiat. In this respect the strandfiat 

 of Helgeland differs entirely from that of Southern Norway. Along the 

 coast south of Sogne Fjord, the submerged strandfiat is insignificant as 

 compared with the extent of the emerged strandfiat. Along the coast 

 northwards the submerged strandfiat increases in extent. In the region 

 of Smolen and Froia the area of the submerged part of the strand flat 

 at least equals that of the emerged part (cf. Fig. 107) and in Helgeland 

 the area of the emerged strandfiat is verv small as compared with that 

 of the submerged strandfiat. 



The depth below sea-level of these submerged plateaus, indicated by 

 the light hatching, is less than 2^ metres, anrl by far the greater part of 

 them have depths less than 10 metres, as is demonstrated by the detailed 

 map Fig. 115 of the Hysvær Plateau to the northwest of \'ega and Sola 

 islands. This map is based upon a small part of No. 54 of the Norwegian 



