499 VOLCANIC REGION OF 
terior of Asia, a volcanic territory, the surface of 
which is upwards of 2500 square geographical miles, 
and which is from 1000 to 1400 miles distant from 
the sea. It fills the half of the longitudinal valley 
situated between the first and second system of 
mountains. The principal seat of volcanic action 
appears to be in the Teen-shan. Perhaps the co- 
lossal Bokhda-ovla is a trachytic formation like 
Chimborazo.” On both sides of the Teen-shan 
violent earthquakes occur. The city of Aksou was 
entirely destroyed at the commencement of the 
eighteenth century by a commotion of this nature. 
In Eastern Siberia the centre of the circle of shocks 
appears to be at Irkutzk, and in the deep basin of 
the Baikal Lake, in the vicinity of which volcanic 
products are observed. But this point of the Al- 
taic range is the extreme limit of these phenomena, 
no earthquakes having been experienced farther to 
the west, in the plains of Siberia, between the Al- 
taic and Uralian ranges, or in any part of the latter. 
The volcanic territory of Bichbalik is to the east 
of the great depression of Asia. To the south and 
west of this internal basin we find two cones in ac- » 
tivity,—Demavend, which is visible from Teheran, 
and Seiban of Ararat, which is covered with vitreous 
lavas. On both sides of the isthmus between the 
Caspian and the Black Sea springs of naphtha and 
mud-eruptions are numerous. 
On the western margin of the great depression, 
if we proceed from the Caucasian isthmus to the 
north and north-west, we arrive at the territory of 
the great horizontal and tertiary deposites of South- 
ern Russia and Poland. Here we find igneous 
rocks piercing the red sandstone of Jekaterinoslav, 
