BURIED CITIES OF THE DESERT OF GOBI. 355 



buried cities are now in process of disinterment that 

 is to say, the sand, while still moving on from age 

 to age, seems to have passed by the sites of these 

 ruins, leaving them now exposed to view. " The 

 walls though only built of sun-dried brick, still stand, 

 and exhibit the holes in which the rafters were 

 inserted, as clearly as if they had only been just used," 

 and though it may seem strange that such structures 

 should be preserved through so many ages, this is 

 readily accounted for by the extreme dryness of the 

 climate. * We shall have more to say, however, upon 

 the marvellously conservative action of these climates 

 further on. Meanwhile, reverting to the question of 

 the sand drift, if we examine the storm-blown surfaces 

 of any great desert or other sand plain, it will be seen 

 that even a small stone, or tuft of grass, by creating 

 an obstacle, will form its own miniature dune, and the 

 sand will be observed to form a rounded heap against 

 it, to windward, and then passing round the sides, to 

 settle, and form a species of triangle, to leeward ; thus 

 marking the cone of the sheltering influence of each 

 obstacle: almost exactly as is done by a rock protruding 

 above the surface in a swiftly flowing stream of water, 

 the cone of shelter influence, being in the latter case 

 marked below the rock, by a calm area, and backwater. 



All deserts seem to be peculiarly liable to sudden 

 storms of wind, some of which are of extraordinary 

 violence, and carry sand, and even small pebbles along 

 with them in a wonderful way ; the air being sometimes 

 so thickly filled with fine particles that it becomes 



* See paper on the Shifting Sands of the Great Desert of Gobi and 

 the Buried Cities, by Sir T. Douglas Forsyth, K.C.S.I., in Journal of 

 R.G.S. Society, Vol. xlvii., 1877. 



