156 Baron Humboldt on the Mountain-chains and 



Chekoy, basalt is found with olivine, cellular amygdaloid, 

 chabasie, and apophyllite *. In the month of February 

 1829, Irktusk suffered greatly from violent earthquakes; 

 and in the month of April following, convulsions were also 

 felt at Ridderski, which were perceived at the bottom of the 

 mines, where they were very severe. But this part of the 

 AltaJf is the extreme limit of the circle of shocks ; farther to the 

 west, in the plains of Siberia, between the Altai and the Ural, 

 as well as along the entire chain of the latter, no motion has hi- 

 therto been observed. The volcano of Pechan, the Aral-tou- 

 be, to the westward of the caverns of sal-ammoniac of Kobok, 

 Ridderski, and the portion of the Altai which abounds in me- 

 tals, are situated for the most part in a direction which but 

 slightly deviates from that of the meridian. Perhaps the Altai* 

 may be comprehended within the circle of the convulsions of the 

 Teen-shan, and the shocks of the Altai, instead of coming only 

 from the east, or from the basin of the Baikal, may also com« 

 from the volcanic country of Bishbalik. In many parts of the 

 new continent, it is clear, that the circles of shocks intersect each 

 other, that is, the same country receives terrestrial convulsions 

 periodically on two different quarters. 



The volcanic territory of Bishbalik is to the eastward of the 

 great depression of the old world. Travellers who have journeyed 

 from Orenburg to Bokhara, relate that at Sussak in the Kara- 

 tau, which forms with the Ala-tau a promontory to the north of 

 the town of Taraz in Turkestan, on the edge of the depression, 

 warm springs spout up. On the south and on the west of the inner 

 basin we find two volcanoes still in activity ; Demavend, which 

 is visible from Tehran, and the Seyban of Ararat, f which is 

 covered with vitrified lava. The trachytes^ porphyries, and ther- 

 mal springs of the Caucasus are well known. On both sides of 

 the isthmus between the Caspian and Black Seas, naphtha springs 

 and volcanoes of mud are numerous. The mud volcano of Ta- 

 man, of which Pallas and Messrs Engelhard and Parrot have 



• Dr Hess, associate of the Academy of Sciences of St Petersburgh, who 

 resided on the borders of the Baikal, and to the south of the lake, from 1826 

 to 1828, gives us reason to expect a geological description of a portion of the 

 remarkable country which he traversed. He frequently observed at Verkh- 

 nei-Oudinsk granite alternating several times with conglomerate. 



•f" The height of Ararat, according to Parrot, is 2700 toises (17,718 feet) ; 

 that of Elbourz, according to Kuppfer, 2560 (16,800 feet) above the level of 

 the ocean. 



