| | | 2I0 WESTWARDS TO LADAK. their origination were in a high degree existent: the ground is dry and level, inexhaustible supplies of detritus are furnished by the surrounding mountains, and as for the wind, the driving and dune-forming agent, surely it leaves nothing to be desired. The reason why there are no sand-formations, notwithstanding that all the conditions are favourable, can scarcely be anything else but this, that the wind blows too hard and is too violent to admit of the origination of dunes. On the surface of the ground there is not even the very thinnest sprinkling of sand and it is useless to look for loose dust: the ground is everywhere hard and consolidated. It consists of extremely finely divided powdery material, but it is pressed together into a solid mass, from which even the hardest wind is unable to remove directly so much as the smallest particle. Yet over this surface, as hard as asphalt, there occur considerable areas of coarse sand, too coarse to be used by the wind as material for dune-building, as well as finer gravel, but scattered so thinly that the underlying yellow soil shows through almost everywhere, after the manner shown |
| | | | | | | | | | in the annexed illustration (fig. I20). All the finer matter, which was once intermingled with these coarser materials, has been blown away, so that the surface is swept perfectly clean of all movable particles, with the exception of such as are too coarse to be transported; and the consequence is that the latter remains behind, like a dissected and divided skeleton. This day we had a striking illustration of the process that goes on. There was virtually a gale blowing from the west. The horses' hoofs always loosen a small quantity of the hard surface; but this day no sooner did the animals lift their feet than the loosened soil was instantaneously blown away. Thus a veil of light dust hung in the wake of the caravan. No sooner was the soil converted into dust than it fell a prey to the wind. When I saw this I readily understood that dunes are unable to originate in this latitudinal valley; they never get an opportunity to form. And even though during a moderate wind a tendency should at any point be manifested towards the formation of dunes, the attempt would be rendered nugatory by the next violent storm, the material being blown away eastwards, until it comes to rest God knows where. The inconceivably violent wind that was then blowing, without a moment's cessation, so violent indeed that we could feel our horses staggering under us and struggling as if advancing in water, was also perfectly clear; there was not the slightest trace of drift-dust to be detected anywhere in that region. The storm of the day before had completely swept away all loose material which may chance to have cumbered the surface of the ground, and in the course of twenty-four hours no further quantity had been able to accumulate, or if it had it was already blown away. Thus during the season, when this »trade wind» blows so unceasingly, we are forced to the conclusion, that every the finest particle which the agencies of disintegration chisel out of the hard rock is blown away almost at the very moment of its birth, or rather rebirth. The relations here are both like and unlike those that prevail in the Desert of Lop. In |
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