II. LIFE-CONDITIONS OF THE MARINE ALGAL 



VEGETATION. 



1. THE NATURE OF THE COAST. 



The coast of Iceland consists partly of rock and partly of sand. 

 The rocky coasts are rich in algal vegetation, while the sandy 

 coast is most frequently a ''desert." Here and there vegetation may 

 be found, however, on the sandy coast, where this is not exposed 

 to violent movement during any length of time. The vegetation then 

 consists of short-lived species. 



The Rocky Coast. This abounds in indentations of various 

 size: inlets, fjords and bays. The size of the fjords varies greatly; 

 for example, the largest, Faxafloi, is ten geographical miles long 

 and twelve geographical miles broad, and Rrei5ifjor5ur is eighteen 

 geographical miles long and ten geographical miles broad. The 

 smaller fjords, on the other hand, are short and narrow indenta- 

 tions. Thus, owing to the indentations on the coast, the exposure 

 is apt to vary greatly. The extreme points and the outer portions 

 of the fjords have, as a rule, an exposed position, while in the 

 interior of the fjord the water is generally calm. 



The rocks on the coast consist of basalt; in some places, how- 

 ever, tuff-coasts exist, and especially on the south coast. The fjord- 

 coasts of Iceland, which comprise South-west, North-west, North 

 and East Iceland, are mainly composed of basalt. The basalt varies 

 considerably but, as far as I have seen, it has no significance as 

 regards the distribution of the species, and no difference is seen, 

 for example, in the vegetation on the dolerite and the ordinary 

 basalt coasts. What is of prime importance to the vegetation is 

 not the rock itself but the nature of its surface. The surface is, as 

 a rule, very uneven, being eroded by water, weather and wind, and 

 furrowed by numerous fissures. Its nature is, therefore, such that 

 the algae can easily attach themselves to it. 



