464 



THE NETHERLANDS. 



In many localities nature aids the work of man. Marine alluvium is deposited 

 upon the banks, or wadden, which separate Friesland from its fringe of islands. 

 After a time they rise above the water, and thousands of birds resort to them, to 

 feed on the molluscs left behind by the retiring tide. It is only, however, after 

 marsh plants and grasses have taken root upon these shining mud- flats, or bliken, that 



Fig. 259. — ÏJIE ZriDERPoiDEu foumeuly. 

 Scale 1 : 76,œ0. 



4-'5P' E.oh- Gr 



4°55; 



1 :Mile 



they are considered " ripe " for embankment. AVhen they reach that stage they arc 

 known as schorron, or kiveldcr, and, if dj'ked off, they yield magnificent crops for 

 forty years in succession, without requiring manure. 



The main dykes, constructed as a defence against the sea, are works of a most 

 formidable nature. The enormous outer piles are tied by planks to an inner row of 



