230 



0. Nordgaard. 



now further north, the change would quite certainly be such that 

 several boreal species would occur there, while some of the arctic 

 ones would die out. or possibly retire into the innermost parts of 

 the fiords. Such a change would take place, because the fiords 

 in this way would have been brought into closer contact with 

 the heat axis of the northwards flowing' current. 



On the relative depths of the fiords. I have made some re- 

 marks in the first part of this work, and reference should also be 

 made to the coast maps. The Finmark fiords are of rather a 

 different character than those in Nordland and Tromso amts. for 

 they are comparatively shallow. An explanation of this has been 

 given by Dr. Andreas Hansen 1 ) who writes: -- ..When the high- 

 land ceases in Finmarkeu, the fiords too acquire another character. 

 They become broader and shallower, less typically formed basins 

 in the loose schist, beds, indeed, for less active and less concen- 

 trated glacier-streams, because here, in the low plateau country- 

 there were not originally such deep canons to determine the course 

 of the glaciers, as on the western slope of the mountains." As a 

 general rule it may be said that there is a deep channel in the 

 fiords with a muddy bottom. On either side, there is a bank or 

 edge of land, which in some cases is evenly sloped, but generally 

 has a most uneven surface. It is, nevertheless, in many instances, 

 possible in a definite section to speak of the angle of inclination 

 of the bank of land. 



It is clear that, the depth being the same, the side surfaces 

 will increase in proportion to the diminution of the angle of in- 

 clination, as will be seen from the figure below, which represents 

 a transverse section through a fiord. 



The side surfaces are thus in inverse proportion to the 

 sinus of the angles of inclination. 



Fijv X. 



If in the one case, the line of intersection between the side- 

 area and the transverse section be s and the angle of inclination 

 a, and in another case the corresponding values be Si and «, we 

 get: — 



sin a 



h 

 sin «] 



s : Sj = sm aj : sin a. 



Are the side surfaces (S and Si) taken to have equally long 

 ground lines, or if one will, shore lines, but with different angles 

 of inclination (a and a,) one gets, according to elementary geome- 

 trical law: — 



S : Si = s : Si but hence follows: — 



S : Si = sin ai : sin a. 



Eg. 



30°, and then: — 



>) Norway, Official Publication for the Paris Exhibition 1900, p. 17. 



a = 90°, oti 



S : Si = ^ : l 

 Si = = 2 S. 



When the angle of inclination is 30°, the side surface will 

 thus be double as large as it is when the land bank is perpendi- 

 cular. 



This little mathematical exposition is valuable in so far as it 

 plainly shows that the space which is available for the distribution 

 of animals depends, to a great extent, upon the angle of inclina- 

 tion of the edge of land. And it gains in interest when it is re- 

 membered that experience proves that the edges, both in the ocean 

 and the fiords, teem with animal life. 



The presence of islands, holms, rocks etc. in a fiord must also 

 be said to be important factors in the animal life of a fiord. They 

 all tend to increase the extent of the particularly productive areas. 



Another important factor in the vegetable and animal life of 

 a given district, is the occurrence of a belt of skerries („skjaer-, 

 gaard"). With respect to navigation, such belts of skerries act as 

 powerful breakwater And as such they are biologically too of 

 importance, and of course the many islands, holms and rocks, with 

 their rich algae vegetation, greatly increase the number of speci- 

 ally productive surfaces. 



Mr. M. Foslie of Trondhjem has kindly given me some in- 

 formation about the influence of such a „skjsergaard" on algae. 

 He writes that where there is none it will, amongst other effects, 

 also be found that the number of species is less. If the coast be 

 an open one, a number of species which require more or less pro- 

 tected spots is as a rule absent. With Mr. Foslie's permis- 

 sion, I quote a part of his letter to me. he writes: ,, Those 

 species which are principally found on the open coast, will also 

 generally be found inside the „skj8ergaard" or in the larger fiords, 

 but usually in the most exposed places, and even there they are 

 not so strong and well developed as on the ocean coast. An illu- 

 stration may be found in the large Laminarians. L. hyperborea 

 and L. digitata are always large and strong in the open sea, but 

 decrease in size and change their shape the further in one finds 

 them. A total absence of some „breakwater" or other often re- 

 sults in the tearing away of large quantities of algae, which the 

 autumn and winter storms drive ashore. I have, for instance, seen 

 immense masses of Laminaria cast in, especially in Berlevaag and 

 Loppen. On the other hand, there are species which are less 

 hardy, and they are smaller on the open coast than in more 

 sheltered places, even if they are found on the coast. They then go 

 further down, where the rush of the waves is less. Therefore, 

 especially along the coast of East Finmark. there are many places 

 where vegetation seems to be poor and only to consist of a few 

 species, while there is comparatively rich vegetation in fairly shel- 

 tered bays." 



An exceedingly important factor in the hydrography and bi- 

 ology of the fiords, is their relative position to the prevailing sum- 

 mer and winter winds, and a closer study of these things will pro- 

 bably throw light upon many matters which hitherto have been 

 uncertain. 



