The Dikes of Holland 



22 I 



conclusions may be drawn as to the shift- 

 ing of the dunes. After having been 

 sacked and burned by the Batavians, re- 

 built again and destroyed once more by 

 the Normans at a later date, the ruins 

 of the castle were during the eighth and 

 ninth centuries gradually covered by the 

 shifting sands of the dunes, which were 

 slowly being transplanted landward by 

 the winds. The ruins disappeared and 

 had been forgotten, when suddenly, after 

 the severe storm of Christmas, 1520, 

 they reappeared once more; but on the 

 beach west of the dunes. Since that 

 time they have in the course of centuries 

 repeatedly been denuded and covered up 

 again, and at the. present day lie sub- 

 merged in the sea. 



RECESSION OF THE COAST LINE 



It has been estimated from these facts 

 that the dunes near Katwijk have mi- 

 grated east a distance of two miles in 

 about eighteen centuries. At other 

 points along the western coast of Hol- 

 land this receding movement has 

 amounted to as much as six and seven 

 miles during the same period. 



It was not easy to put a stop to this 

 alarming recession of the coast and con- 

 sequent loss of land, together with the 

 destruction of numerous flourishing vil- 

 lages. It has been permanently effected, 

 however, by planting on the seaward 

 side of the dunes a species of grass 

 {Arjtndo arenacea), known in Holland 

 as "Helm." This plant can sustain 

 itself very readily in the finest and 

 purest of sands by means of extraordi- 

 narily long and intricate roots, and is 

 therefore well qualified to counteract 

 the shifting of sand. The grass is 

 planted by hand in tufts not quite two 

 feet apart, aligned in rows. That this 

 was a laborious piece of work needs no 

 demonstration, when it is borne in rnind 

 that there extend along the coast of 

 Holland a chain of dunes of a total 

 length of 200 miles, varying in width 



from 400 yards to three miles, while the 

 elevations range from 60 to 200 feet 

 above sea-level. In other places forest 

 growth has been started on the dunes 

 13'ing further inland, and the results 

 have been very gratifying. 



1,500 SQUARE MII.es OF LAND SUB- 

 MERGED IN THE INTERIOR AND THE 

 FORMATION OF ZUIDER ZEE 



The retrogression of the dunes was a 

 source of alarm; yet, on account of its 

 slowness, the movement had not at first 

 made itself manifest. Very serious 

 changes had taken place, however, in 

 the interior within a comparatively 

 short period. Furious storms in the 

 North Sea during the years 693, 782, 

 839, and again in 1170, 1230, and 1237 

 had caused a washing away of large 

 sections of peat land situated between 

 Lake Flevo and the North Sea. This 

 wholesale destruction of land culmi- 

 nated in 1250, 1287, and 1295, when 

 during the spring tides of those years 

 Lake Flevo had become an inlet of the 

 North Sea. It is estimated that this 

 loss amounted to nearly 1,500 square 

 miles of land, and submerged a number 

 of flourishing villages. Heavy dikes 

 were then built, inclosing the so-formed 

 Zuider Zee, except at such points where 

 it communicated with other bodies of 

 water, in order to check all further en- 

 croachments on the land. Its form has 

 since been practically the same as now 

 appears on our maps. 



With the advent of the fourteenth 

 centur}^ began a period of active dike- 

 building in Holland. Not onlj^ the 

 Zuider Zee had swallowed much rich, 

 arable land, but many of the interior 

 bodies of water, at times of storms, were 

 making similar trouble, and inundations 

 caused by the large rivers were frequent. 

 Obviously, as the country became more 

 closely settled and land became more 

 valuable, every new inundation caused 

 more loss of life and property than had 



