22 GEOLOGICAL MEMOIRS, 



Tertiaries) some years ago ; but Vicomte d'Arehiac* doubted the 

 deposits in question to be really of Eocene age, as the late Prof. E. 

 Forbes had believed them to be on account of some of their organic 

 remains. Capt. Spratt himself subsequently regarded the freshwater 

 deposits described by him to be probably of Miocene date ; neverthe- 

 less his own investigations and those of other geologists indicate 

 them to possess an extraordinary range of diffusion. 



In a paperf " On the Freshwater deposits of Bessarabia, Moldavia, 

 Wallachia, and Bulgaria," by Capt. Spratt, read before the Geological 

 Society of London on January 4th, 1860, the author mentions the 

 existence of freshwater deposits on the banks of the Yalpuk Lake in 

 South Bessarabia, containing organic remains similar to those from 

 other localities of the sediments of the great Middle Tertiary fresh- 

 water lake. Among them are freshwater species of Oardium, occur- 

 ring also (together with. Dreissena polymorpha) in the freshwater strata 

 of the Dardanelles and elsewhere. After some search, Capt. Spratt 

 found similar forms living in the Yalpuk Lake, and was thereby 

 confirmed in his conviction of the above-mentioned tertiary basin 

 having really been occupied by fresh water. He supposes a bar (the 

 Isaktcha hills, now broken through by the Danube) to have separated 

 the level of the Black Sea from that of the lake then existing in 

 Bessarabia and the Danubian provinces. The conditions of the 

 enormous freshwater plains in Eastern Europe and in Asia Minor may 

 have been disturbed, he thinks, by volcanic eruptions establishing a 

 communication between the Black Sea and the Mediterranean, alter- 

 ing the level of these regions, and probably in connexion with the 

 'formation of enormous gravel deposits along the foot of the Car- 

 pathian chain. 



It has appeared desirable that the Geologists of the Vienna Imp. 

 Institute should collect the facts recently obtained with respect to the 

 occurrence of freshwater strata in Hungary and Transylvania, and 

 bring them in connexion with those observed by Capt. Spratt. This 

 subject becomes still more interesting when considered in relation with 

 the Caspian Sea and the Aral Lake. These two enormous lakes, with 

 water very poor in salt, may indeed afford some idea of the freshwater 

 basins of S.E. Europe, as supposed by Capt. Spratt to have existed 

 during the Middle Tertiary period. According to the statements of 

 MM. Walmer, Gobel, Eose, Abich, and others, in the water in the 

 north portion of the Caspian Sea, where the rivers Ural and Volga fall 

 into it, there is not above 016 to 0-6 per cent., and in the other por- 

 tions not above 1*2 to l-4per cent, of salt ; while Pisani has found a 

 per-centage of 1-6 to 1-7 in the water of the Bosphorus near Bujuk- 

 dere; and Erman has recently stated the per-centage of salt in the 

 Mediterranean to be 3*72 in the harbour of Marseilles, 3-79 between 

 Port Vendre and Barcelona, 3*81 between Barcelona and Valencia, 



* Hist. Pi-ogres Creol. ii. p. 907. 



+ For the printed abstract of this and the other papers read before the Geolo- 

 gical Society, the author and bis colleagues are indebted to the Officers of the 

 Society, who forward them promptly and regularly to Count Marschall. 



