In one case a floating island, which had attached itself to the shore, continued to float about for a long time after it was torn off by a flood, and was solid enough to keep a pond of fresh water upon it sweet, though the water in which it was swimming had become brackish from the irruption of the sea. After the hay is cut, cattle are pastured, and occasionally root-crops grown upon these islands, and they sometimes have large trees growing upon them.
When the turf or peat has been cut, leaving water less than a yard deep, Equisetum limosum grows at once, and is followed by the second class of marsh plants mentioned above. Their roots do not become detached from the bottom in such shallow water, but form ordinary turf or peat. These processes are so rapid that a thickness of from three to six feet of turf is formed in half a century, and many men have lived to mow grass where they had fished in their boyhood, and to cut turf twice in the same spot. In Ireland the growth of peat is said to be much more rapid. Elisee Reclus, La Terre, i., 591, 592. But see Asbjornsen, Torv og Torvdrift, ii., 29, 30.
Captain Gilliss says that before Lake Taguataga in Chili was drained, there were in it islands composed of dead plants matted together to a thickness of from four to six feet, and with trees of medium size growing upon them. These islands floated before the wind "with their trees and browsing cattle."—United States Naval Astronomical Expedition to the Southern Hemisphere, i., pp. 16, 17.] fascines being everywhere used to bind and compact the mass together. This operation was completed in 1848, and three steam-pumps were then employed for five years in discharging the water. The whole enterprise was conducted at the expense of the state, and in 1853 the recovered lands were offered for sale for its benefit. Up to 1858, forty-two thousand acres had been sold at not far from sixteen pounds sterling or seventy-seven dollars an acre, amounting altogether to L661,000 sterling or $3,200,000. The unsold lands were valued at more than L6,000 or nearly $30,000, and as the total cost was L764,500 or about $3,700,000, the direct loss to the state, exclusive of interest on the capital expended, may be stated at L100,000 or something less than $500,000.
The success of this operation has encouraged others of like nature in Holland. The Zuid Plas, which covered 11,500 acres and was two feet deeper than the Lake of Haarlem, has been drained, and a similar work now in course of execution on an arm of the Scheld, will recover about 35,000 acres.
In a country like the United States, of almost boundless extent of sparsely inhabited territory, such an expenditure for such an object would be poor economy. But Holland has a narrow domain, great pecuniary resources, an excessively crowded population, and a consequent need of enlarged room and opportunity for the exercise of industry. Under such circumstances, and especially with an exposure to dangers so formidable, there is no question of the wisdom of the measure. It has already provided homes and occupation for more than five thousand citizens, and furnished a profitable investment for a private capital of not less than L400,000 sterling or $2,000,000, which has been expended in improvements over and above the purchase money of the soil; and the greater part of this sum, as well as of the cost of drainage, has been paid as a compensation for labor. The excess of governmental expenditure over the receipts, if employed in constructing ships of war or fortifications, would have added little to the military strength of the kingdom; but the increase of territory, the multiplication of homes and firesides which the people have an interest in defending, and the augmentation of agricultural resources, constitute a stronger bulwark against foreign invasion than a ship of the line or a fortress armed with a hundred cannon.
Draining of the Zuiderzee.
I have referred to the draining of the Lake of Haarlem as an operation of great geographical as well as economical and mechanical interest. A much more gigantic project, of a similar character, is now engaging the attention of the Netherlandish engineers. It is proposed to drain the great salt-water basin called the Zuiderzee. This inland sea covers an area of not less than two thousand square miles, or about one million three hundred thousand acres. The seaward half, or that portion lying north-west of a line drawn from Enkhuizen to Stavoren, is believed to have been converted from a marsh to an open bay since the fifth century after Christ, and this change is ascribed, partly if not wholly, to the interference of man with the order of nature. The Zuiderzee communicates with the sea by at least six considerable channels, separated from each other by low islands, and the tide rises within the basin to the height of three feet. To drain the Zuiderzee, these channels must first be closed and the passage of the tidal flood through them cut off. If this be done, the coast currents will be restored approximately to the lines they followed fourteen or fifteen centuries ago, and thero can be little doubt that an appreciable effect will thus be produced upon all the tidal phenomena of that coast, and, of course, upon the maritime geography of Holland.
A ring-dike and canal must then be constructed around the landward side of the basin, to exclude and carry off the freshwater streams which now empty into it. One of these, the Ijssel, a considerable river, has a course of eighty miles, and is, in fact, one of the outlets of the Rhine, though augmented by the waters of several independent tributaries. These preparations being made, and perhaps transverse dikes erected at convenient points for dividing the gulf into smaller portions, the water must be pumped out by machinery, in substantially the same way as in the case of the Lake of Haarlem. [Footnote: The dependence of man upon the aid of spontaneous nature, in his most arduous material works, is curiously illustrated by the fact that one of the most serious difficulties to be encountered in executing this gigantic scheme is that of procuring brushwood for the fascines to be employed in the embankments. See Diggelen's pamphlet, "Groote Werken in Nederland.">[ No safe calculations can be made as to the expenditure of time and money required for the execution of this stupendous enterprise, but I believe its practicability is not denied by competent judges, though doubts are entertained as to its financial expediency. [Footnote: The plan at present most in favor is that which proposes the drainage of only a portion of the southern half of the Zuiderzee, which covers not far from 400,000 acres. The project for the construction of a ship-canal directly from Amsterdam to the North Sea, now in course of execution, embraces the drainage of the Ij, a nearly land-locked basin communicating with the Zuiderzee and covering more than 12,000 acres. See official reports on these projects in Droogmaking vom het zuidelyk gedeelte der Zuiderzee, te s' Gravenhage, 1868, 4to.] The geographical results of this improvement would be analogous to those of the draining of the Lake of Haarlem, but many times multiplied in extent, and its meteorological effects, though perhaps not perceptible on the coast, could hardly fail to be appreciable in the interior of Holland.
The bearing of the works I have noticed, and of others similar in character, upon the social and moral, as well as the purely economical, interests of the people of the Netherlands, has induced me to describe them more in detail than the general purpose of this volume may be thought to justify; but if we consider them simply from a geographical point of view, we shall find that they are possessed of no small importance as modifications of the natural condition of terrestrial surface. There is good reason to believe that before the establishment of a partially civilized race upon the territory now occupied by Dutch, Frisic, and Low German communities, the grounds not exposed to inundation were overgrown with dense woods; that the lowlands between these forests and the sea-coasts were marshes, covered and partially solidified by a thick matting of peat-plants and shrubs interspersed with trees; and that even the sand-dunes of the shore were protected by a vegetable growth which, in a great measure, prevented the drifting and translocation of them.
The present causes of river and coast erosion existed, indeed, at the period in question; but some of them must have acted with less intensity, there were strong natural safeguards against the influence of marine and fresh-water currents, and the conflicting tendencies had arrived at a condition of approximate equilibrium, which permitted but slow and gradual changes in the face of nature. The destruction of the forests around the sources and along the valleys of the rivers by man gave them a more torrential character. The felling of the trees, and the extirpation of the shrubbery upon the fens by domestic cattle, deprived the surface of its cohesion and consistence, and the cutting of peat for fuel opened cavities in it, which, filling at once with water, rapidly extended themselves by abrasion of their borders, and finally enlarged to pools, lakes, and gulfs, like the Lake of Haarlem and the northern part of the Zuiderzee. The cutting of the wood and the depasturing of the grasses upon the sand-dunes converted them from solid bulwarks against the ocean to loose accumulations of dust, which every sea-breeze drove farther landward, burying, perhaps, fertile soil and choking up water-courses on one side, and exposing the coast to erosion by the sea upon the other.