360 COSMOS. 



great wall of Magog (Madjoudj). Ame"de"e Jaubert, to whom 

 we are indebted for important supplements to the Nubian 

 geographers, has shown that the fires which burn on the 

 slope of the Coca'ia have nothing volcanic in their nature 

 (Asie Centrale, t. ii, p. 99). Edrisi places the Lake of Te- 

 hama further to the south. I think I have said enough to 

 show the probability of the Tehama being identical with the 

 great Lake of Balkasch, into which the Hi flows, and which 

 is only 180 miles further south. A century and a half later 

 than Edrisi, Marco Polo placed the wall of Magog among 

 the mountains of In-schan, to the east of the elevated plain of 

 Gobi, in the direction of the River Hoang-ho and the Chinese 

 wall, respecting which, singularly enough, the famous Vene- 

 tian traveller is as silent as he is on the subject of the use of 

 tea. The In-shan, the limit of the territory of Prester John, 

 may be regarded as the eastern prolongation of the Thian- 

 schan (Asie Centrale, t. ii, pp. 92104). 



The two conical volcanic mountains, the Petschan and 

 Hotshen of Turfan, which formerly emitted lava, and which 

 are separated from each other at a distance of about 420 

 geographical miles by the gigantic block of mountains called 

 the Bogdo-Oola, crowned with eternal snow and ice, have 

 long been erroneously considered an isolated volcanic group. 

 I think I have shown that the volcanic action north and 

 south of the long chain of the Thian-schan here, as well as 

 in the Caucasus, stands in close geognostic connection with 

 the limits of the circle of terrestrial commotion, the hot- 

 springs, the solfataras, the sal-ammoniacal fissures and beds 

 of rock-salt. 



According to the view I have already frequently ex- 

 pressed, and in which the writer most profoundly acquainted 

 with the Caucasian mountain system (Abich) now coin- 

 cides, the Caucasus itself is only a continuation of the ridge 

 of the volcanic Thian-schan and Asferah on the other side 

 of the great Aralo- Caspian depression. 67 This is therefore 

 the place, in connection with the phenomena of the Thian- 

 shan, to cite as belonging to pre-historical periods the four 

 extinct volcanoes of Elburuz, 18,494 feet in height, Ararat 

 17,112 feet, Kasbegk 16,532 feet, and Savalan 15,760 feet 



i7 Asie Centrale, t. ii, pp. 9, and 5458. See also page 208, 

 note 61, of the present volume. 



