The marked characteristic of the Dunes, as we have already said, is their mobility, which renders them a constant menace for the neighbouring populations. To the wind which creates them they owe their frequent changes and their inland movement. While the sea eats into the coast, assisted by the breezes which gradually sweep clear the ground before it, the Dunes extend, and drive before them the shallow lakes: these in their turn encroach upon the Landes, and until now man has been constrained to recoil, step by step, before his threefold enemy. It is in this phenomenon, rather than in the ungrateful soil of the Landes, that we must seek the cause of the curse which has seemed so long to rest upon this country-side. You must go back some twenty centuries to trace the origin of the Dunes of Gascony. Fourteen or fifteen hundred years ago the coast north of the Adour was inhabited, and comparatively flourishing. Mimizan was then a town and a sea-port, from which were exported the resinous products of the neighbouring forests. The Normans disembarked there on several occasions. Under its walls, in 506, was fought a great battle between the allied Goths and Ostrogoths on the one side, and the Béarnais, commanded by a bishop of Lescar, on the other. Both town and port to-day are buried under the sands. "Full fathom five" lie church and convent, and the busy street, the noisy mart, and the once peaceful home. The present village has nearly perished: the Dune was not three yards from the church when its progress was recently arrested. Other cities, laid down in old charts of the country, but of which not a trace remains, have in this manner disappeared, and entire forests have been ingulfed, now under the sands of the Dunes, now under the sands and waves of the sea. Some parts of the chain have been rendered to a great extent immovable by the vegetation which has gradually covered them, and these have opposed a formidable obstacle to the encroachments of the sands. Yet here and there the barrier has been defied. For example, in the forest of Biscarosse the movable Dunes, actually sweeping over the ancient hills, have not only filled up the valleys, but ingulfed a great number of pines, and raised themselves several yards above the crest of the oldest trees, planted on the summit of the highest hills. In whose favour, in this struggle of science against the elements, will the victory eventually be decided? The question is one which the future alone can resolve.[13] CHAPTER IV. WILD SCENES OF ENGLAND:--DARTMOOR AND THE FEN COUNTRY.