•580 THE LANDES OF GASCONY. 



sand-flood as tlie " vanguard of those vast drifts wMch, advancing 

 from the southeast, threaten eventually to overwhelm Babylon 

 and Baghdad." 



An observation of Layard, cited by Loftus, appears to me to 

 furnish a possible explanation of this irruption. He " passed two 

 or three places where the sand, issuing from the earth like water, 

 is called ' Aioun-er-rummal,' sand springs. " These " springs " are 

 very probably merely the drifting of sand from the ancient sub- 

 soil, where the protecting crust of aquatic deposit and vegetable 

 earth has been broken through, as in the case of the drift which 

 arose from the upturning of an oak mentioned on a former page. 

 When the valley of the Euphrates was regularly irrigated and 

 cultivated, the underlying sands were bound by moisture, alluvial 

 shme, and vegetation ; but now that all improvement is neglected, 

 and the surface, no longer watered, has become parched, powdery 

 and naked, a mere accidental fissure in the superficial stratum 

 may soon be enlarged to a wide opening, that will let in loose 

 sand enough to overwhelm a province. 



The Landes of Gascony. 



The most remarkable sand-plain of France lies at the south- 

 western extremity of the empire, and is generally known as the 

 Landes, or heaths, of Gascony. Clave thus describes it : " Com- 

 posed of pure sand, resting on an impermeable stratum called 

 alios, the soil of the Landes was, for centuries, considered inca- 

 pable of cultivation.* Parched in summer, drowned in winter, 



plain in Cape Cod: "Here, about one thousand acres were entirely blown 



away to the depth, in many places, of ten feet Not a green thing was 



visible except the whortleberries, which tufted a few lonely hillocks rising to 

 the height of the original surface and prevented by this defence from being 

 blown away also. These, although they varied the prospect, added to the 

 gloom by their strongly picturesque appearance, by marking exactly the origi- 

 nal level of the plain, and by showing us in this manner the immensity of the 

 mass which had been thus carried away by the wind. The beach grass had 

 been planted here, and the ground had been formerly enclosed ; but the gates 

 had been left open, and the cattle had destroyed this invaluable plant." 



* The alios, which from its color and consistence was supposed to be a fer- 

 ruginous formation, appears from recent observations to contain little iron 

 and to owe most of its pecuUar properties to vegetable elements carried down 

 into the soil by the percolation of rain-water. See Revue des Eaux et Forita 

 foi 1870, p. 301. 



