26 H. JONSSON 



The rocky coast is, as a rule, of solid rock, consisting of preglacial 

 basaltic lava. Postglacial basaltic lava is found, nevertheless, in some 

 places, as for example on Snasfellsnes. In many places, large stretches 

 of the coast are covered with debris (Ur5) from the mountains. 

 Where the debris or the new lava predominates the surface is ge- 

 nerally very uneven, and one then finds distinct elevations with 

 large and small depressions interposed; such a coast is usually 

 covered with an abundant and multifarious algal vegetation, if the 

 conditions are in other respects favourable to the existence of algae. 



There is no range of skerries (Skaergaard) as there is, for example, 

 on the coast of Norway. Yet a number of islands and rocks occur 

 in the fjords, especially in Brei5ifj6r5ur. In this fjord are found 

 indications of a range of skerries running parallel with the coast 

 and along a considerable stretch of it, and marking the outward 

 limit of the Zosfera-vegetation. 



The Sandy Coast. Almost the entire coast of S.Iceland is 

 sandy shore or gravel shore. As a rule, such bottoms afford a mobile 

 substratum because each wave which breaks on the beach shifts the 

 particles backwards and forwards. A sandy coast is also met with, 

 here and there, in other parts of the country, but is then found, 

 as a rule, alternating with rocky parts; thus, the sandy or gravelly 

 shore is often predominant at the head of small indentations which 

 at the sides are bounded by projecting masses of rocks. 



Clayey Shore is also found fairly frequently in the interior 

 of the fjords. 



The rocky coast is, as a rule, abundantly overgrown, and this 

 is frequently the case also with the sublittoral gravel-bottom, while 

 the sand and gravel bottoms laid bare periodically by the shifting tide 

 are not, as a rule, overgrown, and, in any case, only with short- 

 lived species. On clayey and muddy bottoms, on the other hand, 

 alga3 are seldom or never found, while Zostera often covers such a 

 bottom and forms submarine "green meadows." 



Despite the small u desert" areas, one may say that the coasts 

 are covered with a zone of continuous algal vegetation - if we ex- 

 clude the eastern portion of S. Iceland. This algal zone varies greatly 

 in width, accommodating itself to the precipitousness of the coast. 

 In a bay as shallow as Faxafloi the algal vegetation has a great 

 extension seawards, while it is far more limited, for example, on 

 the steeply descending submarine declivities in the fjords of the 

 east coast. 



