GENERAL CHARACTERISTICS AND GEOLOGICAL HISTORY 



361 



Bogachev (1932) thinks that for the Middle-Miocene fauna such a ' refuge ' was 

 preserved in Asia (in Turkestan) and from it the fauna penetrated first into the 

 Maeotic basin and later into the Akchagyl. Other ' refuges ' may have existed 

 for the Sarmatian and Pontic faunas. Other investigators assume a repeated 

 penetration of Mediterranean forms from the west, from the Mediterranean 

 Sea. If one takes into account the fact, for example, that in the present-day 

 Gulf of Taganrog there exist side by side the completely different Mediter- 

 ranean and Caspian faunas which have occupied this body of water in turn 

 during the post-Tertiary changes of salinity, the Suess conception of a ' refuge ' 

 becomes wholly realistic. Table 141 sets out the history, described above, of the 

 Black and Caspian Seas and their faunas. 



Table 141 



Middle 



Miocene 

 Upper 



Miocene 



Pliocene 



Middle Miocene basin of full salinity 



(Remains of Tethys) 

 Brackish-water Sarmatian basin (to the east beyond the Aral Sea, 



to the west up to the middle Danube lowland) 

 Towards the end a great reduction in size, then again an enlarge- 

 ment and transition 

 Maeotic basin; semi-marine 'Euxine' conditions [A. Derzhavin 

 (1928) thinks that the Black Sea was connected with the Sea of 

 Marmora] 

 Pontic basin, considerable loss of salinity of the Maeotic basin. 



'Caspian' conditions with a lowered salinity 

 Towards the end the Black, Caspian and Aral Seas are separated 



from each other 

 Cimmerian basin The basin of productive deposits. 



Kuyalnits basin Akchagyl basin (was for a time 



connected with the Kuyalnits 

 basin) 

 Apsheron basin (was temporarily 

 connected with the Chaudin 

 basin) 

 Baku stage 



Chaudin basin (was con- 

 nected through the Bos- 

 phorus with the low-salinity 

 Sea of Marmora, had no 

 connection with the Medi- 

 terranean) 



Ancient Euxine basin (Cas- 

 pian type of fauna) 



A connection is established 

 with the Mediterranean 

 (Karangatsky Sea) 



Ancient Caspian basin (with a tem- 

 porary link through a flow into 

 the Black Sea along the Kumo- 

 Manych depression) 



Post-Tertiary 

 Period 



Novo-Euxine basin 

 Contemporary phase 



Post-glacial transgression, 

 temporary basin 



Con- 



The Black Sea during the Quaternary Period 



During the Quaternary Period the salinity changes of the Black Sea were 

 caused, on the one hand, by the existence or the absence of a connection with 



