364 



BIOLOGY OF THE SEAS OF THE U.S.S.R. 

 Table 143 



Era 



Basin Salinity 



Level 



Connection 



with with 



Black Sea Turan basin 



Comparison 



Baku 



Lower 

 Caspian 



Upper 

 Caspian 



Con- 

 temporary 



Baku 



Average 



Khazar Very low 



Khvalynsk Slight 

 salinity 



Con- 

 temporary 



Average, Linked with Outflow of Ice Age 



more or less Ancient fresh 



stable Euxine basin water 



Fluctuating, Interrupted Outflow 



rise and fall ceased 



Rise Connected Outflow 



with Novo- along Uzboi 

 Euxine basin 



Interruption Outflow 

 stopped 



Post-glacial 

 period 



4. Ancient Euxine period, Sea strait. Free exchange of faunas 

 Lower Caspian era 



(Khazar basin) 



5. Upper Euxine period, Sea strait. Probable migration of fauna from 

 Upper Caspian era the east 



(Khvalynsk basin) 



6. Contemporary era Drying up. Erosion by river waters 



History of the Aral Sea 



Contrary to the earlier view regarding the expansion of the Sea during the 

 greatest Caspian transgression, in one of the interglacial eras (Khvalynsk 

 era) through the Uzboi into the Sarakamysh hollow and the Aral Sea, A. 

 Archangelsky considers (1915) that the body of water occupying this area 

 had no connection with the Caspian Sea and was a huge completely fresh- 

 water lake with an outflow through the Uzboi (thick deposits of clay and sand 

 with Dreissensia, Limnaea, Unio and others). Later on this lake became much 

 smaller in size, and subsequently it was again filled with water as a result of 

 the climate becoming damper ; a system of brackish lakes was formed in the 

 depressions of the Sarakamysh hollow and along the Uzboi, and at this time 

 Cardium edule penetrated into the Aral Sea. With the transition to the present 

 era the climate again became dry and the Aral Sea acquired its present out- 

 line. 



A. Behning (1938) discovered a whole series of forms of the Caspian fauna 

 in the lakes of the old bed of the Uzboi (Yaskhan, Karatogelek, Topiatan). 

 Besides several fish, among which the later Mediterranean immigrant 

 Atherina mochon pontica caspia is of particular importance, he listed for 

 those bodies of water the molluscs Dreissensia polymorpha, Theodoxus 

 pal/asi, Th. danubialis, the crustaceans Dikerogammarus haemobaphes, Ponto- 

 gammarus crassus, Corophium curvispinum and the little fish Proterorhinus 



