196 T. F. Jamieson — Inland Seas of the Glacial Period. 



The Bead Sea. 



In 1865 M. Lartet announced that he had found evidence which 

 led him to conclude that towards the end of the Tertiary, or at the 

 commencement of the Quaternary period, the surface of the Dead 

 Sea must have had an elevation of more than a hundred metres 

 above its present level, and that it had deposited up to that 

 height stratified beds of marl full of gypsum and salt, showing 

 that the lake was even then extremely salt. He failed, however, 

 to discover any vestige of organic remains in these marl beds, which 

 extend a considerable way north and south of the present extremities 

 of the lake. Alluding to Hooker's discovery of glacier moraines on 

 the Lebanon, Lartet infers that a climate which clothed these moun- 

 tains with permanent snow and ice would have lessened evaporation, 

 and led to an increase of the waters of the Dead Sea and other inland 

 lakes of Asia somewhat as I had suggested.^ 



More recently Canon Tristram has noticed indications which lead 

 him to believe that the Dead Sea had attained a much higher level 

 than that mentioned by Lartet. Doubtless it must have gone 

 through many phases of rise and fall, but its history will require to 

 be more fully worked out before we can arrive at satisfactory con- 

 clusions on the subject. 



The Aralo-Caspian Basin. 



The same may be said of this great depression. There is ample 

 evidence that the waters here had formerly a much wider extension, 

 but the exact time, or times, when this occurred — although geologi- 

 cally recent — has yet to be determined. Dr. S. P. Woodward, in his 

 Manual of the Mollusca, says the Aralo-Caspian limestone indicates 

 the former presence of a great inland sea — larger than the Medi- 

 terranean — at a time previous to that of the Mammoth and the 

 Siberian Ehinoceros. This steppe-limestone rises to a level of 200 

 or 300 feet above the present level of the Caspian. 



The fact of the waters of the Caspian and Aral being only brackish, 

 and by no means veiy salt, leads me to think that the basin has not 

 been a close one for a very long period. General von Helmersen 

 found well-preserved specimens of two kinds of shells, viz. Cardium 

 edule and Dreissena polymorpha, in the sands of the desert of Karakum. 

 Both these species still live in the Caspian. And Helmersen expi'esses 

 his belief that the entire country from the Aral on to the sandy 

 deserts of Akkum is an old sea-bottom (Quart. Journ. Geol. Soc. 

 1869, vol. XXV. Memoirs, p. 8). 



The present surface of the Caspian is 84 feet below that of the 

 Black Sea, and according to Major Wood a rise of 220 feet would 

 cause the waters of the Caspian to overflow the watershed of the 

 Tobolsk, a tributary of the Obi. 



According to the same authority, a rise of 23 feet in the waters of 

 the Black Sea would cause it to overflow into the Caspian by the 

 line of the Manytsch. 



^ Bulletin of the Geol. Soc. of France, second series, vol. 22, p. 420. 



