124 THE DESICCATION OF LATER GEOLOGICAL TIMES. 



tnent of the world, is an admitted feet. But it is possible to go much far- 

 ther than this, and to say, that over extensive regions, where once the light 

 of civilization shone with its brightest effulgence, and both the arts and 

 the sciences had acquired a remarkable development, there now a scanty 

 nomad population, living from hand to mouth, without a single attribute 

 worthy of respect, just drags along a miserable existence, continually strug- 

 gling against the forces of nature, and palpably losing ground from century 

 to century. Let the reader, for instance, contrast the present condition of 

 Arabia with its former one, when it led the van of scientific inquiry, and 

 he will have a good illustration of the kind of change to which the writer 

 is here making reference. 



That the cause of this immense going backward of the region to the 

 east of the Mediterranean is exclusively physical in character is not intended 

 to be asserted ; but that there is a physical cause which must have had a 

 most powerful effect in bringing about the condition of things here indicated 

 is beyond a doubt. It admits of demonstration that the countries in ques- 

 tion have become very materially drier than they were during the earlier 

 historic period ; and that, consequently, life is no longer possible there, ex- 

 cept under conditions which are not compatible with density of population 

 or with intellectual vigor. 



It will not be possible, at the present time, to do m^re than give a few of 

 the salient facts which support the above assertion. It may, however, be 

 unhesitatingly declared that the evidence is abundant, and that it all points 

 in one direction. Here, however, as in the preceding section, a full discus- 

 sion cannot be entered upon. Only a few of the prominent facts can be 

 presented, and it must be reserved for another chapter to endeavor to make 

 out how far the phenomena of desiccation are to be ascribed to a purely 

 climatological cause, and how far to preceding orographic changes. 



Decidedly the most striking event presenting itself to us, in the region 

 in question, as an evidence of desiccation within the historic period, is the 

 greatly diminished area of water-surface in the Aralo-Caspian basin, a 

 problem which has much occupied the attention of physical geographers 

 at various times, and especially within the past half-century, the literature 

 relating to this subject being already quite voluminous. Even to name all 

 the authorities who have written in regard to the changes which have taken 

 place in the physical geography of the region in question in historic and 

 prehistoric times, with reference especially to the channels of the rivers 



