No, Sahara as a whole is not below sea-level; it is not the dry bed of a recent ocean; and it is not as flat as the proverbial pancake all over.  Part of it, indeed, is very mountainous, and all of it is more or less varied in level.  The Upper Sahara consists of a rocky plateau, rising at times into considerable peaks; the Lower, to which it descends by a steep slope, is ‘a vast depression of clay and sand,’ but still for the most part standing high above sea-level.  No portion of the Upper Sahara is less than 1,300 feet high—­a good deal higher than Dartmoor or Derbyshire.  Most of the Lower reaches from two to three hundred feet—­quite as elevated as Essex or Leicester.  The few spots below sea-level consist of the beds of ancient lakes, now much shrunk by evaporation, owing to the present rainless condition of the country; the soil around these is deep in gypsum, and the water itself is considerably salter than the sea.  That, however, is always the case with fresh-water lakes in their last dotage, as American geologists have amply proved in the case of the Great Salt Lake of Utah.  Moving sand undoubtedly covers a large space in both divisions of the desert, but according to Sir Lambert Playfair, our best modern authority on the subject, it occupies not more than one-third part of the entire Algerian Sahara.  Elsewhere rock, clay, and muddy lake are the prevailing features, interspersed with not infrequent date-groves and villages, the product of artesian wells, or excavated spaces, or river oases.  Even Sahara, in short, to give it its due, is not by any means so black as it’s painted.

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