184 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DeC. 17, 



this valley ; and probably also it was continued by the Maritza 

 valley (in Thrace) up to the foot of the Balkan. It probably co- 

 vered also the basin now formed by the Sea of Marmora ; for an un- 

 broken series of these freshwater deposits extends from the entrance 

 of the Dardanelles to St. Stephano, as will be seen by the fossils 

 which have been recently sent to the Society from several localities 

 on this line. 



The whole of this region was, in my opinion, covered by a fresh- 

 water lake of Miocene and Pliocene age. 



I shall at another opportunity touch upon the freshwater deposits 

 on the Asiatic side of the Archipelago, in Mitylene and Tenedos, 

 and at the Dardanelles and the Sea of Marmora : these comprise 

 additional fragments of the great ancient Oriental lake, which I have 

 lately had the opportunity of examining. 



2. On the Analysis of Waters fro7n the Turko-Persian Fron- 

 tier*. By Dr. Thomas Richardson and E. J. J. Browell, 

 Esq. In a letter from Dr. Richardson to W. K. Loftus, Esq., 

 F.G.S. 



[The following is a report on six samples of water from the Lake of 

 Vanf, the small Lake of Ardchek, situated to the east of the former, 

 and their vicinity, not far south-west of Ararat. They were brought 

 home by Mr. W, Kennett Loftus. — Edit.] 



The water marked No. 1 1 has a very remarkable composition, con- 

 taining only traces of the ordinary saline matter and a large pro- 

 portion of the two alkaline earths, lime and magnesia. It is diffi- 

 cult to surmise whence it has obtained these constituents, unless 

 by assuming that it was originally a water coming off dolomite and 

 subsequently passing through a bed of gypsum, under which cir- 

 cumstances a change of its constituents would take place, by a re- 

 combination among the acids and bases. 



No. 10 is not unlike some of the waters which we have met with 

 in collieries in the Newcastle district, where a large quantity of com- 

 mon salt is accompanied with oxide of iron. The sources of lime 

 are very numerous. 



Nos. 6 to 9 belong to a very limited class of waters found in Hun- 

 gary, Egypt, &c., all more or less rich in carbonate of soda. The 

 lake near Debretzin in Hungary contains so much of this salt, that, 

 during the evaporation in summer, it is regularly collected and sold 

 as an article of trade. The waters of the natron-lakes in the desert 

 on the west bank of the Nile have a similar character, where the salt 



* For the analyses of other samples of water from lakes and springs on the 

 Turko-Persian Frontier, see Mr. Witt's paper in the Philos. Magaz. 4th ser. vol. xi. 

 p. 257. 



t See Quart. Journ. Geol. Soc. vol. xi. p. 317, &c. 



