RODENTS OF LIBYA 11 



The Gebel es Soda and the Gebel el Harug el Asued of central Libya 

 are mountains of this type. Both of these gebels have been regarded 

 as the "Black Gebel" because of the color of the lava of which they 

 are composed. Other mountain complexes of the Libyan interior which 

 reach sizable proportions include the Acacus Mountains near Ghat in 

 the extreme southwestern Fezzan and the Gebel Archenu, Gebel 

 Uweinat, and the outliers of the Tibesti Mountains in southern 

 Cyrenaica. In many areas of the eastern Fezzan and southern Cyre- 

 naica, rocky formations are present in the form of buttes and mesas in 

 the midst of hamadas or sand seas. Cufra Oasis is surrounded by a 

 complex of steep-sided gebels, and Bzema Oasis, which is located deep 

 within the Sand Sea of Rebianna, is situated at the base of an imposing 

 monolith. 



The Cyrenaican Plateau 



The massif of the Cyrenaican Plateau of extreme northern Cy- 

 renaica, with its high rolling slopes and deep canyons, differs strikingly 

 from all other physical features of Libya. The Cyrenaican Plateau 

 proper encompasses the region of Cyrenaica from Benghazi in the 

 west to Martuba in the east. Its southern terminus is near El Mechili 

 where it grades imperceptibly into the inland hamada. The Gebel el 

 Achdar, which comprises the northernmost and highest portions of 

 the plateau, extends almost to the Mediterranean Sea where it 

 terminates in a rocky terraced escarpment. These escarpments pro- 

 vide a sharp contrast in relief to the low-lying hamadas and coastal 

 plain. In many places the coastal "gebel" encroaches onto the coastal 

 plain causing its virtual elimination. Deep canyons with rugged 

 precipitous slopes have their origin in the interior of the plateau and 

 dissect the coastal escarpment. 



The highest point in the plateau is 2,844 feet above sea level lo- 

 cated on the Gebel el Achdar between Slonta and El Faidia. The 

 higher portions of the Cyrenaican Plateau have characteristic broad, 

 rolling slopes, and the canyons are less rocky and have less precipitous 

 margins than those nearer the coast. Some areas of the plateau are 

 almost flat and allow sizable agricultural endeavors. The Barce Valley, 

 in the western part of the plateau, is a basin of internal drainage and 

 is unique in Libya in this respect. During periods of unusually high 

 rainfall, fresh water accumulates in the bottom of the valley to a 

 depth of several feet and thus forms a rather sizable lake. 



The Tripolitanian Gebel 



The Gebel Nefusa of northwestern Tripolitania is less clearly de- 

 fined by discrete physical elements. It includes the high tablelands 

 extending roughly from the Tunisian border in the west to the vicinity 



