The coast-line extends in a double curve from south-west to north-east, and is formed by a row of sand dunes, 171 m. in length, fringed by a broad sandy beach descending very gradually into the sea. In the north and south, however, this line is Coast. broken by the inlets of the sea which form the Frisian and the South Holland and Zeeland islands respectively; but the dunes themselves are found continued along the seaward side of these islands, thus indicating the original continuity of the coast-line. The breadth of the dunes naturally varies greatly, the maximum width of about 4375 yds. being found at Schoorl, north-west of Alkmaar. The average height of the individual dune-tops is not above 33 ft., but attains a maximum of 197 ft. at the High Blinkert, near Haarlem. The steepness of the dunes on the side towards the sea is caused by the continual erosion, probably traceable, in part at least, to the channel current (which at mean tide has a velocity of 14 or 15 in. per second), and to the strong west or north-west winds which carry off large quantities of material. This alteration of coast-line appears at Loosduinen, where the moor or fenland formerly developed behind the dunes now crops out on the shore amid the sand, being pressed to the compactness of lignite by the weight of the sand drifted over it. Again, the remains of the Roman camp Brittenburg or Huis te Britten, which originally lay within the dunes and, after being covered by them, emerged again in 1520, were, in 1694, 1600 paces out to sea, opposite Katwijk; while, besides Katwijk itself, several other villages of the west coast, as Domburg, Scheveningen, Egmond, have been removed further inland. The tendency of the dunes to drift off on the landward side is prevented by the planting of bent-grass (Arundo arenaria), whose long roots serve to bind the sand together. It must be further remarked that both the “dune-pans,” or depressions, which are naturally marshy through their defective drainage, and the geest grounds—that is, the grounds along the foot of the downs—have been in various places either planted with wood or turned into arable and pasture land; while the numerous springs at the base of the dunes are of the utmost value to the great cities situated on the marshy soil inland, the example set by Amsterdam in 1853 in supplying itself with this water having been readily followed by Leiden, the Hague, Flushing, &c.

As already remarked, the coast-line of Holland breaks up into a series of islands at its northern and southern extremities. The principal sea-inlets in the north are the Texel Gat or Marsdiep and the Vlie, which lead past the chain of the Frisian Islands into the large inland sea or gulf called the Zuider Zee, and the Wadden or “shallows,” which extend along the shores of Friesland and Groningen as far as the Dollart and the mouth of the Ems. The inland sea-board thus formed consists of low coasts of sea-clay protected by dikes, and of some high diluvial strata which rise far enough above the level of the sea to make dikes unnecessary, as in the case of the Gooi hills between Naarden and the Eem, the Veluwe hills between Nykerk and Elburg, and the steep cliffs of the Gaasterland between Oude Mirdum and Stavoren. The Dollart was formed in 1277 by the inundation of the Ems basin, more than thirty villages being destroyed at once. The Zuider Zee and the bay in the Frisian coast known as the Lauwers Zee also gradually came into existence in the 13th century. The extensive sea-arms forming the South Holland and Zeeland archipelago are the Hont or West Scheldt, the East Scheldt, the Grevelingen (communicating with Krammer and the Volkerak) and the Haringvliet, which after being joined by the Volkerak is known as the Hollandsch Diep. These inlets were formerly of much greater extent than now, but are gradually closing up owing to the accumulation of mud deposits, and no longer have the same freedom of communication with one another. At the head of the Hollandsch Diep is the celebrated railway bridge of the Moerdyk (1868-1871) 1607 yds. in length; and above this bridge lies the Biesbosch (“reed forest”), a group of marshy islands formed by a disastrous inundation in 1421, when seventy-two villages and upwards of 100,000 lives were destroyed.

Besides the dunes the only hilly regions of Holland are the southern half of the province of Limburg, the neighbourhood of Nijmwegen, the hills of Utrecht, including the Gooi hills, the Veluwe region in Gelderland, the isolated hills in the middle and Relief and levels. east of Overysel and the Hondsrug range in Drente. The remainder of the country is flat, and shows a regular downward slope from south-east to north-west, in which direction the rivers mainly flow. The elevation of the surface of the country ranges between the extreme height of 1057 ft. near Vaals in the farthest corner of Limburg, and 16-20 ft. below the Amsterdam zero[2] in some of the drained lands in the western half of the country. In fact, one quarter of the whole kingdom, consisting of the provinces of North and South Holland, the western portion of Utrecht as far as the Vaart Rhine, Zeeland, except the southern part of Zeeland-Flanders, and the north-west part of North Brabant, lies below the Amsterdam zero; and altogether 38% of the country, or all that part lying west of a line drawn through Groningen, Utrecht and Antwerp, lies within one metre above the Amsterdam zero and would be submerged if the sea broke down the barrier of dunes and dikes. This difference between the eastern and western divisions of Holland has its counterpart in the landscape and the nature of the soil. The western division consists of low fen or clay soil and presents a monotonous expanse of rich meadow-land, carefully drained in regular lines of canals bordered by stunted willows, and dotted over with windmills, the sails of canal craft and the clumps of elm and poplar which surround each isolated farm-house. The landscape of the eastern division is considered less typical. Here the soil consists mainly of sand and gravel, and the prevailing scenery is formed of waste heaths and patches of wood, while here and there fertile meadows extend along the banks of the streams, and the land is laid out in the highly regular manner characteristic of fen reclamation (see [Drente]).

The entire drainage of Holland is into the North Sea. The three principal rivers are the Rhine, the Maas (Meuse) and the Scheldt (Schelde), and all three have their origin outside the country, whilst the Scheldt has its mouth only in Holland, Rivers. giving its name to the two broad inlets of the sea which bound the Zeeland islands. The Rhine in its course through Holland is merely the parent stream of several important branches, splitting up into Rhine and Waal, Rhine and Ysel, Crooked Rhine and Lek (which takes two-thirds of the waters), and at Utrecht into Old Rhine and Vecht, finally reaching the sea through the sluices at Katwijk as little more than a drainage canal. The Ysel and the Vecht flow to the Zuider Zee; the other branches to the North Sea. The Maas, whose course is almost parallel to that of the Rhine, follows in a wide curve the general slope of the country, receiving the Roer, the Mark and the Aa. Towards its mouth its waters find their way into all the channels intersecting the South Holland archipelago. The main stream joining the Waal at Gorinchem flows on to Dordrecht as the Merwede, and is continued thence to the sea by the Old Maas, the North, and the New Maas, the New Maas being formed by the junction of the Lek and the North. From Gorinchem the New Merwede (constructed in the second half of the 19th century) extends between dykes through the marshes of the Biesbosch to the Hollandsch Diep. These great rivers render very important service as waterways. The mean velocity of their flow seldom exceeds 4.9 ft., but rises to 6.4 ft. when the river is high. In the lower reaches of the streams the velocity and slope are of course affected by the tides. In the Waal ordinary high water is perceptible as far up as Zalt Bommel in Gelderland, in the Lek the maximum limits or ordinary and spring tides are at Vianen and Kuilenburg respectively, in the Ysel above the Katerveer at the junction of the Willemsvaart and past Wyhe midway between Zwolle and Deventer; and in the Maas near Heusden and at Well in Limburg. Into the Zuider Zee there also flow the Kuinder, the Zwarte Water, with its tributary the Vecht, and the Eem. The total length of navigable channels is about 1150 m., but sand banks and shallows not infrequently impede the shipping traffic at low water during the summer. The smaller streams are often of great importance. Except where they rise in the fens they call into life a strip of fertile grassland in the midst of the barren sand, and are responsible for the existence of many villages along their banks. Following the example of the great Kampen irrigation canal in Belgium, artificial irrigation is also practised by means of some of the smaller streams, especially in North Brabant, Drente and Overysel, and in the absence of streams, canals and sluices are sometimes specially constructed to perform the same service. The low-lying spaces at the confluences of the rivers, being readily laid under water, have been not infrequently chosen as sites for fortresses. As a matter of course, the streams are also turned to account in connexion with the canal system—the Dommel, Berkel, Vecht, Regge, Holland Ysel, Gouwe, Rotte, Schie, Spaarne, Zaan, Amstel, Dieze, Amer, Mark, Zwarte Water, Kuinder and the numerous Aas in Drente and Groningen being the most important in this respect.

It is unnecessary to mention the names of the numerous marshy lakes which exist, especially in Friesland and Groningen, and are connected with rivers or streamlets. Those of Friesland are of note for the abundance of their fish and their beauty Lakes. of situation, on which last account the Uddelermeer in Gelderland is also celebrated. The Rockanje Lake near Brielle is remarkable for the strong salty solution which covers even the growing reeds with a hard crust. Many of the lakes are nothing more than deep pits or marshes from which the peat has been extracted.

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Dikes.—The circumstance that so much of Holland is below the sea-level necessarily exercises a very important influence on the drainage, the climate and the sanitary conditions of the country, as well as on its defence by means of inundation. The endiking of low lands against the sea which had been quietly proceeding during the first eleven centuries of the Christian era, received a fresh impetus in the 12th and 13th centuries from the fact that the level of the sea then became higher in relation to that of the land. This fact is illustrated by the broadening of river mouths and estuaries at this time, and the beginning of the formation of the Zuider Zee. A new feature in diking was the construction of dams or sluices across the mouths of rivers, sometimes with important consequences for the villages situated on the spot. Thus the dam on the Amstel (1257) was the origin of Amsterdam, and the dam on the Ye gave rise to Edam. But Holland’s chief protection against inundation is its long line of sand dunes, in which only two real breaches have been effected during the centuries of erosion. These are represented by the famous sea dikes called the Westkapelle dike and the Hondsbossche Zeewering, or sea-defence, which were begun respectively in the first and second halves of the 15th century. The first extends for a distance of over 4000 yds. between the villages of Westkapelle and Domburg in the island of Walcheren; the second is about 4900 yds. long, and extends from Kamperduin to near Petten, whence it is continued for another 1100 yds. by the Pettemer dike. These two sea dikes were reconstructed by the state at great expense between the year 1860 and 1884, having consisted before that time of little more than a protected sand dike. The earthen dikes are protected by stone-slopes and by piles, and at the more dangerous points also by zinkstukken (sinking pieces), artificial structures of brushwood laden with stones, and measuring some 400 yds. in circuit, by means of which the current is to some extent turned aside. The Westkapelle dike, 12,468 ft. long, has a seaward slope of 300 ft., and is protected by rows of piles and basalt blocks. On its ridge, 39 ft. broad, there is not only a roadway but a service railway. The cost of its upkeep is more than £6000 a year, and of the Hondsbossche Zeewering £2000 a year. When it is remembered that the woodwork is infested by the pile worm (Teredo navalis), the ravages of which were discovered in 1731, the labour and expense incurred in the construction and maintenance of the sea dikes now existing may be imagined. In other parts of the coast the dunes, though not pierced through, have become so wasted by erosion as to require artificial strengthening. This is afforded, either by means of a so-called sleeping dike (slaperdyk) behind the weak spot, as, for instance, between Kadzand and Breskens in Zeeland-Flanders, and again between ’s Gravenzande and Loosduinen; or by means of piers or breakwaters (hoofden, heads) projecting at intervals into the sea and composed of piles, or brushwood and stones. The first of such breakwaters was that constructed in 1857 at the north end of the island of Goeree, and extends over 100 yds. into the sea at low water. Similar constructions are to be found on the seaward side of the islands of Walcheren, Schouwen and Voorne, and between ’s Gravenzande and Scheveningen, and Katwijk and Noordwijk. Owing to the obstruction which they offer to drifting sands, artificial dunes are in course of time formed about them, and in this way they become at once more effective and less costly to maintain. The firm and regular dunes which now run from Petten to Kallantsoog (formerly an island), and thence northwards to Huisduinen, were thus formed about the Zyper (1617) and Koegras (1610) dikes respectively. From Huisduinen to Nieuwediep the dunes are replaced by the famous Helder sea-wall. The shores of the Zuider Zee and the Wadden, and the Frisian and Zuider Zee islands, are also partially protected by dikes. In more than one quarter the dikes have been repeatedly extended so as to enclose land conquered from the sea, the work of reclamation being aided by a natural process. Layer upon layer of clay is deposited by the sea in front of the dikes, until a new fringe has been added to the coast-line on which sea-grasses grasses begin to grow. Upon these clay-lands (kwelders) horses, cattle and sheep are at last able to pasture at low tide, and in course of time they are in turn endiked.

River dikes are as necessary as sea dikes, elevated banks being found only in a few places, as on the Lower Rhine. Owing to the unsuitability of the foundations, Dutch dikes are usually marked by a great width, which at the crown varies between 13 and 26 ft. The height of the dike ranges to 40 in. above high water-level. Between the dikes and the stream lie “forelands” (interwaarden), which are usually submerged in winter, and frequently lie 1 or 2 yds, higher than the country within the dikes. These forelands also offer in course of time an opportunity for endiking and reclamation. In this way the towns of Rotterdam, Schiedam, Vlaardingen and Maasluis have all gradually extended over the Maas dike in order to keep in touch with the river, and the small town of Delftshaven is built altogether on the outer side of the same dike.

Impoldering.—The first step in the reclamation of land is to “impolder” it, or convert it into a “polder” (i.e. a section of artificially drained land), by surrounding it with dikes or quays for the two-fold purpose of protecting it from all further inundation from outside and of controlling the amount of water inside. Impoldering for its own sake or on a large scale was impossible as long as the means of drainage were restricted. But in the beginning of the 15th century new possibilities were revealed by the adaptation of the windmill to the purpose of pumping water. It was gradually recognized that the masses of water which collected wherever peat-digging had been carried on were an unnecessary menace to the neighbouring lands, and also that a more enduring source of profit lay in the bed of the fertile sea-clay under the peat. It became usual, therefore, to make the subsequent drainage of the land a condition of the extraction of peat from it, this condition being established by proclamation in 1595.