XII.] THE CAUCASIC PEOPLES. 451 



an inlet but by "evaporation," which process is however somehow 

 confined to this inlet, and does not affect either the Mediterranean 

 or the Atlantic itself. Nor is it explained how the oceanic waters 

 were prevented from rushing in according " as the Sahara sea 

 evaporated to become a desert." The attempt to evolve a 

 " Eurafrican race " in such an impossible area necessarily broke 

 down, other endless perplexities being involved in the initial 

 geological misconception. 



Not only was the Sahara dry land in pleistocene times, but 

 it stood then at a considerably higher altitude than at present, 

 although its mean elevation is still estimated by Chavanne at 

 1500 feet above sea-level. "Quaternary deposits cover wide 

 areas, and were at one time supposed to be of marine origin. 

 It was even held that the great sand dunes must have been 

 formed under the sea ; but at this date it is scarcely necessary 

 to discuss such a view. The advocates of a Quaternary Sahara 

 Sea argued chiefly from the discovery of marine shells at several 

 points in the middle of the Sahara. But Tournouer has shown 

 that to call in the aid of a great ocean in order to explain the 

 presence of one or two shells is a needless expenditure of energy 1 ." 



At an altitude of probably over 2000 feet the Sahara must 

 have enjoyed an almost ideal climate during late pliocene and 

 pleistocene times, when Europe was exposed to more than one 

 glacial invasion, and to a large extent covered at long intervals 

 by a succession of solid ice-caps. We now know that these stony 

 and sandy wastes were traversed in all directions by great rivers, 

 such as the Massarawa trending south to the Niger, or the 

 Igharghar' 2 flowing north to the Mediterranean, and that these 

 now dry beds may still be traced for hundreds of miles by chains 



1 Ph. Lake, The Geology of the Sahara, in Science Progress, July, 1895. 



- This name, meaning in Berber "running water," has been handed down 

 from a time when the Igharghar was still a mighty stream with a northerly 

 course of some 800 miles, draining an area of many thousand square miles, in 

 which there is not at present a single perennial brooklet. It would appear 

 that even crocodiles still survive from those remote times in the so-called Lake 

 Miharo of the Tassili district, where von Bary detected very distinct traces of 

 their presence in 1876. Mr A. E. Pease also refers to a Frenchman "who had 

 satisfied himself of the existence of crocodiles cut off in ages long ago from 

 watercourses that have disappeared" (Contemp. Review, July, 1896). 



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