GEOLOGY OP THE SAHARA. 249 



Atlantic, over which the Atlas chain extends, was formerly 

 insulated, and in that state formed the celebrated Atlantis^ 

 —is not destitute of geological probability.* 



2. Geology of the Desert, or Sahara Region. — The se- 

 cond, or Sahara region, is eminently characterized by its 

 vast desert of sand, the greatest and most frightful on the 

 face of the earth. On the east it is bounded by a rocky 

 limestone wall to the west of the Nile, and a series of oases 

 and deserts extending from Darfiir to the Libyan Desert : 

 on the north by a range of oases and the flat and interest- 

 ing country along the southern foot of the Atlas chain : on 

 the west by the ocean : and, towards the south, it ceases in 

 about 15° N.lat., sloping gradually down to the fertile and 

 well-watered country of Bomou on the east, Houssa in the 

 centre, and the regions to the westward of Timbuctoo. 

 Houssa and Bomou comprehend that region 'of Africa 

 known by the name Soudan, or Land of the Blacks. 



The Sahara may be considered as divided into an eastern 

 and a western half. Its eastern and smaller halt is more 

 varied by rocks, and cliflfs, and oases, than the western and 

 larger, which forms a vast sea of moving sand, well merit- 

 ing the Arabian name, Sahara Bela-ma, or sea without 

 water. The Western Sahara is bounded on the east in a 

 line which passes through Fezzan, extending towards the 

 south into Soudan, and towards the north to the Atlas. 

 On many parts of the seacoast it extends under the sea, 

 forming enormous sand banks ; and along the coast there 

 are extensive ranges of downs or sand hills. The coast is 

 very dangerous, and much dreaded by seamen. Ship- 

 wrecks frequently take place, and the unfortunate survivors 

 are carried off by the savages into a state of the most de- 

 plorable slavery. Cape Blanco, so well known to mariners, 

 is not a rocky headland, but a flat sandy projecting white 

 tongue of land, destitute of vegetation. The sand hills 

 continue down to Cape Verde, — a promontory distinguished 

 by its two lofty hills of sand, rising to a height of 600 feet, 

 and overlooking the smaller surrounding downs, and form- 

 ing a warning landmark, seen by sailors at a great distance. 



* The particular geology of the Northern Region, which will include 

 descriptions of Morocco, Fez, Algiers Tunis, and Tripoli, will appear in 

 a future volume of this Library, the present volume being confined prin- 

 cipally to tUe Central and Southern Regions of Africa. 



