1 92 I. No. 1 I. THE STRANDFLAT AND ISOSTASY I 33 



Fig. 114. Map of coast of Northern Helgeland, northward Continuation of the map Fig. 114. 

 Besides the Isobaths for every 52 metres of depth, the Isobath for 25 metres is drawn 



with dotted line. 

 I Vandved Island. II Donna Island. Ill Lokta Island. IV Lifjell on the mainland. V Hugla 

 Island. VI Handnesoi. VII Tomma Island. VIII Hestmannoi. IX Nesoi. X Sornesøi 



and L^Migvaer. 



more resistant than tlie limestone and the mica-schists. None the less 

 the strandfiat often cuts horizontally through the various rocks, without 

 anv ap[)reciable difference in height, straight to the foot of the mountains 

 and hills rising abruptly and steeply above its plane. 



The region of Solvær and Lovunden (see Fig. 114) may be mentioned 

 as an illustrative example. The many islands of Solvær consist of mica 

 schist and limestone on the southeastern islands, gabbro on the south- 

 western islands, granite on the northern, and mica-schist, limestome, 

 gabbro, and granite on the northeastern islands. Lovunden mountain, 

 as well as the low islets to the east, south, and west of it, are built up 

 of gneiss, while the low islands of Lovundvær to the north and northeast 

 consist of granite, gneiss, mica-schist, and limestone. All these many 

 islands, built up of rocks varying so widely in their power of resistance, 

 are cut down to an almost perfectly horizontal plane at about 10 metres 

 above sea-level, and the plane extends at the same level to the foot of 

 Lovunden, which rises abruptly as an isolated 'stack' to 619 metres above 

 the sea [cf. Xansen, 1904, PI. \', Fig. i]. 



This is a convincing piece of evidence that the plane of the strandfiat 

 has been cut by an agency working horizontally, /. c. by the shore erosion, 

 and cannot have been formed by the vertically working subaërial denu- 

 dation, nor by glacial erosion, which would necessarily have produced a 

 marked difference in height between the regions of more and of less 

 resistant rocks. The plane cuts in many cases so evenly across areas of 

 entirely different rocks that it can only be explained as an effect of the 

 shore erosion by frost. The wave erosion cannot have had very great 

 direct effect, because it would produce greater difference in the level of 

 the rocks with different power of resistance. In other cases there is such 

 a difference, which may be accounted for by the wave erosion. 



The mountains rising as 'stacks' above the strandfiat consist very 

 often of granite, e. g. on Vega and Søla islands, but in some cases, e. g. on 

 Lovunden and Hestmannen (Hestmannoi), they are built up 'of gneiss, 

 although the gneiss in other regions has been much denuded, and forms 

 parts of the very low and level plane of the strandfiat. 



The reason why the strandfiat is so well-developed along the coast 

 of Helgeland may be especially two fold: On the one hand the severe 

 climate of this northern region has been especially favourable for the 

 subaërial denudation as well as for the shore erosion. It is for this latter 

 reason that in postglacial time the now raised shore-ledges have been 



