124 FRIDTJOF NANSEN. M.-N. Kl. 



/■ruta is cliic-fly huilt u|» <>\ ,L;raiiilc wliicli in soiiiu places is pressed. 

 Aloiij^- its soullicni coast thcrr is ilioritic f^Miciss. J'Voia is very low and 

 iiKist of its area beloiif^rs to the strandflat, with some hills anrl riflges rising 

 above its plane, especially in the southern or s^nitheastern part of the is- 

 lanrl (see ¥\<^. 107), to lieights of al)(Ait 50 t(j 70 metres. 



1'he height of the strandflat of i'Voia is 20 to 30 metres above the 

 sea in its western part an'l along the northern and eastern coast. In its 

 imier and southern i)arts llic land is mostly more than 30 metres high. 

 The surface is considerabJN- less even than the surfacj of Smolen, and 

 has many ridges and de[jressions. This is obvitnisly due to its geological 

 structure, the granite giving (jften a rough and broken surface. As 

 Schetelig has pointed out to me, the unevenness in this case may especially 

 have been caused 1)\- alternations of regions with more resistant porphyria 

 granite and regions with pressed granite or gneisses, less resistant to 

 erosion. 



Along most parts of the coast of Hitteren anrl also along the south 

 and west (or northwest) coast of Froia the submerged strandflat is cotn- 

 parativelv narrow and is much dissected and uneven. This is also the case 

 along the coast of the mainland (see Fig. 107). But to the north of Froia 

 a submerged strandflat with hundreds of islands and skerries extends 

 20 kilometres into the sea, and continues 50 kilometres towards the north- 

 east, comprising the extensive region of the many low and flat Froan Is- 

 lands (see Fig. 107). The surface of this submerged platform is much 

 dissected as the map may give the impression. But in some parts, c. g. in 

 the region of Sillen, Bu Skjær, and Gjeit wSkjær northwest of Froia (see 

 map Fig. 107), the surface is extremely level over considerable areas, 

 forming horizontal plains near sea-level or only a few metres below it, 

 and having well defined edges at depths of less than 10 metres. 



The width of the strandflat from the edge of this partly submerged 

 platform to the foot of the higher land on Hitteren is 43 kilometres. But 

 if we reckon it to extend across the Hitteren to the foot of the mountains 

 on the mainland the width will be 58 kilometres. The width of the strand- 

 flat from the edge of the outermost submerged platform outside Smolen 

 to the foot of the mountains on Tustern is 40 kilometres. The distance 

 from the outer edge of the submerged platform of the Froan Islands to 

 the foot of the high mountains on the mainland is about 46 kilometres. 



The strandflat is here conspicuously much wider than in any region 

 along the Norwegian coast to the south, and is partly developed to fuller 

 maturity. The reasons may be several. 



On the one hand the geological structure has favoured the formation 

 of a strandflat. By the Caledonian mountain folding a fairly low land 

 was made to emerge along the top of one or two folding ridges far out 

 in a stormv sea, where it was exposed to the full furv of the marine 

 denudation. This low land was to a great extent luiilt up of rocks, dioritic 



