346 DESERT SANDS 



action ; the work is all done by sun and wind. Under 

 these circumstances, the rocks crumble away very slowly 

 by mere exposure into small fragments, which the wind 

 knocks off and blows about the surface, forming sand or 

 dust of them in all convenient hollows. The frequent 

 currents, produced by the heated air that lies upon the 

 basking layer of sand, continually keep the surface agitated, 

 and so blow about the sand and grind one piece against 

 the other till it becomes ever finer and finer. Thus for 

 the most part the hollows or valleys of deserts are filled by 

 plains of bare sand, while their higher portions consist 

 rather of barren, rocky mountains or table-land. 



The effect upon whatever animal or vegetable life can 

 manage here and there to survive under such circumstances 

 is very peculiar. Deserts are the most exacting of all 

 known environments, and they compel their inhabitants 

 with profound imperiousness to knuckle under to their 

 prejudices and preconceptions in ten thousand particulars. 



To begin with, all the smaller denizens of the desert — 

 whether butterflies, beetles, birds, or lizards — must be 

 quite uniformly isabelline or sand-coloured. This uni- 

 versal determination of the desert-haunting creatures to 

 fall in with the fashion and to harmonise with their 

 surroundings adds considerably to the painfully mono- 

 tonous effect of desert scenery. A green plant, a blue 

 butterfly, a red and yellow bird, a black or bronze- 

 coloured beetle or lizard would improve the artistic aspect 

 of the desert not a little. But no ; the animals will hear 

 nothing of such gaudy hues ; with Quaker uniformity they 

 will clothe themselves in dove-colour ; they will all wear a 

 sandy pepper-and-salt with as great unanimity as the 

 ladies of the Court (on receipt of orders) wear Court 

 mourning for the late lamented King of the Tongataboo 

 Islands. 



