^ DESERTS AND THEIR INHABITANTS 



If popular errors connected with matters scientific are hard 

 to kill, still more is this the case when the erroneous 

 opinions have been held by scientists themselves. The 

 idea that flints and other stones grow is, I have good 

 reason to believe, still far from extinct among the non- 

 scientific, and it is not improbable that there are persons 

 possessing some acquaintance with science who still cherish 

 the belief that deserts are uninterrupted plains of smooth 

 sand, originally deposited at the bottom of the sea, from 

 which they have been raised at a comparatively recent 

 epoch. At any rate, there are several books, published 

 not very many years ago, in which it is stated in so many 

 words that the Sahara represents the bed of an ancient 

 sea, which formerly separated Northern Africa from the 

 regions to the southward of the tropics. 



As a matter of fact, these opinions with regard to the 

 origin and nature of deserts are scarcely, if at all, less 

 erroneous than the deeply ingrained popular superstition 

 as to the growth of flints and pudding-stones. And a 

 little reflection will show that the idea of the loose sands 

 of the desert being a marine deposit must necessarily be 

 erroneous. Apart from the difficulty of accounting for the 

 accumulation of such vast tracts of sand on the marine 

 hypothesis, it will be noticed, in the first place, that desert- 

 sands are not stratified in the manner characteristic of 



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