178 J. E. S. MOORE. 



great instability of the regions in which Tanganyika lies ; an 

 instability which has been quite sufficient to corJ^ceivably 

 account for any amount of upheavals and depressions which 

 may have been requisite for the marine contamination of that 

 lake. The valleys in which the north of Nyassa, Lakes Tan- 

 ganyika, Albert Edward, Albert, Baringo, Rudolph, and about 

 twenty-seven minor lakes lie, are really part of a connected 

 series of depressions formed by faults which run approximately 

 north and south through an immense distance, and can be 

 traced as far as Berbera on the Red Sea, thence north along 

 the Red Sea shore itself, the coasts of which are to a great 

 extent of similar formation, and they terminate finally in or 

 about the Dead Sea, and the valleys of the tributaries of the 

 Jordan.^ All the country traversed by this immense series of 

 faults from the north of Nyassa in the south, to the ancient 

 sites of Sodom and Gomorrah in the north, is filled with 

 native traditions of catastrophes, of floods, of earthquakes, of 

 volcanic outbursts, and the like ; and the geological investiga- 

 tions of Gregory ^ and others have shown that much of the 

 above faulting and volcanic activity must have occurred, 

 geologically speaking, in quite recent times. The existence 

 of these singular rift-valley faults has divided the African 

 lakes into two distinct series ; one series of lakes being always, 

 like Nyassa, Tanganyika, and Rudolph, long, narrow, and deep ; 

 the other, like the Victoria Nyanza, Bangweolo, and Shirwa, 

 broad, shallow, and round. 



We have, therefore, evidence of great geological instability 

 in the very regions in which the Halolimnic animals now live ; 

 but, like the palseontological record, it affords no insight as to 

 how or when, if Tanganyika ever was connected with the sea, 

 this connection could really have been made; but it is a sin- 

 gular fact that the one lake in which the Halolimnic animals 

 now live is that which lies at the bottom of the biggest and 

 most conspicuous inland rift.^ 



^ See Suess, 'Die Briicke des Oust Afrika.' 



» The Great Rift Valley. 



* The southern two thirds of Nyassa is not in a rift ; and in contrast to 



