The origin of the bare sand-spots may be traced to the agency of man. The immigrating nomadic populations required for their herds not wood, but pasture and tillable land, and mercilessly cleared away the forest. The land thereby became arid, and wherever a pasture or meadow was not established, the sand, deprived of its covering, became a prey to the winds. Even if this view be regarded as a hypothesis that can not be proved, it is at least illustrated and made comprehensible by events which are historically authenticated or are still taking place. When the Turks were driven out of Hungary, the sand-tracts, for the most part, lay waste. The Italian Griselini, who traveled through the Banat under a commission of the Empress Maria Theresa, wrote: "For nearly eight German miles in length and from nine to ten thousand fathoms in breadth, the sand, when it is not moist, is so fugitive that it is taken up by the wind and deposited in little hills of various heights."
The once well-clothed level sand region of Tidsvild in Zealand, where a religious house was built in the twelfth century, was, at a later date, through carelessness and the destruction of the woods during the Swedish invasion of 1658-'60, given up to the ravages of the winds. Wide tracts and even valleys, like Tomb, and, in 1730, Tibirke, were overwhelmed with sand. The Government was aroused by these disasters, and earnestly undertook the work of irrigating the sand. The enterprise was successful, a fact of which a memorial stone erected in the territory bears witness, in an inscription in Danish, German, and Latin, relating, "The drift sand was watered at the command of Kings Frederick and Christian, by the faithful industry of Warden Frederick von Granu and Roehl's skilled hand." A similar instance of the letting loose of the drift-sand through the careless destruction of the woods is recorded in East Prussia.
There are cases even now where, through the greed or ignorance of man, bare sand-tracts are allowed to be formed in the midst of cultivated lands. This takes place, for example, where grass-land is pastured to excess, or the turf is trodden out by the too frequent passage of large herds over the same spot. Exposure to the direction of the prevailing winds, subjecting broken spots to frequent sweepings and promoting the washing out of ruts by rains, poor farming, and careless burning of the shrubbery are also dangerous, and in Hungary have led to the enactment of laws regulating the treatment of sand-lands.
As has already been mentioned, the noxious quality of sand consists not so much in its own infertility as in its being subject to transportation by strong winds and deposition upon fertile spots, where it buries and destroys the lower vegetation. When it is thus driven or flies away from its original place it receives
