ГУ. G-eneral view of the factors which contribute 

 to the formation of the deposits. 



Å. brief survey will now be given of the degree in which 

 the various factors already mentioned contribute to the forma- 

 tion of the deposits. The different ingredients in these must 

 have been mainly derived from one or other of the following 

 four sources, 1) the land, 2) the drift ice, 3) moraines at the 

 bottom of the sea and 4) solid rocks at the bottom of the sea. 

 It is impossible to say for certain which of these factors plays 

 the most prominent part in the district now under consider- 

 ation , we can only say that they have each contributed con- 

 siderably to the formation of the deposits. The material they 

 supply is of a very diverse nature. 



I. The transport direct from land which, in other parts 

 of the earth, is by far the most important of the factors which 

 supply the bottom of the sea with mineral material is here 

 subordinate to the other factors mentioned. The mode of 

 origin of the material belonging to this class is somewhat 

 varied; probably only a small amount is loosened directly by 

 the waves lashing against the rocks of the coast, the greater 

 part being conveyed hither by larger or smaller rivers; some- 

 times the wind will also be able to convey a considerable 

 quantity of material into the sea. At any rate the particles 



