THE DIKES OF HOLLAND 



By Gerard H. Matthes, United States Geological 



Survey 



TO obtain an idea of the important 

 role the dikes have played in 

 the development of the Nether- 

 lands, and of the problems with which 

 the inhabitants of that country have had 

 to contend, it is necessary in the first 

 place to understand how the soil of the 

 Netherlands was formed, and what the 

 peculiar conditions are that have ren- 

 dered the existence of this unique little 

 country possible. A few words concern- 

 ing the geology of the region, which 

 dates back to a time by no means re- 

 mote, will therefore be of interest. 



Geologically speaking, a large portion 

 of the Netherlands may be said to have 

 been formed only yesterday. This por- 

 tion, which comprises the western and 

 most interesting half of the kingdom, 

 owes its origin to the alluvial deposits 

 brought there by three large rivers — the 

 Rhine, the Meuse, and the Schelde — 

 the estuaries of which unite to form 

 what at first glance appears to be a delta. 

 The large amount of sediment discharged 

 by these rivers, together with the action 

 of tides and currents in the North Sea, 

 were the primary causes of the forma- 

 tion of extensive series of sandbanks 

 and bars ofE the coast, and as these 

 banks grew higher and finally became 

 exposed to the action of the wind at 

 times of low water, there came into ex- 

 istence sandhills, commonly known as 

 dunes. The coast in those days partook 

 much of the nature of a " haff, ' ' such 

 as is found today on the German coast 

 on the Baltic Sea, or along our own 

 coast, notably at Pamlico and Albemarle 

 Sounds. A long tongue of land running 

 parallel with the coast inclosed a body 

 of shallow water into which discharged 



the three rivers. It is natural to sup- 

 pose that after the formation of this 

 haff, sedimentation progressed rapidly. 

 Heavy deposits of clay gathered in its 

 quiet waters, and later, as the haff grew 

 more shallow and aquatic vegetation be- 



THS U£Tf/£HLANDS 



came luxurious, extensive marshes came 

 into existence, and the great peat beds 

 which cover so large a part of the area 

 of Holland at the present day were 

 formed. 



Interesting as are the successive steps 

 in the formation of the country during 

 those early days, space will not permit 

 here to treat of them at length. Suffice 

 it to be said that after the general level 

 of the deposits had reached that of the 

 sea, there arose vast forests, which at one 

 time covered almost the entire country 



