Caucasus and the Crimea. 401 



Akaltsikhe. Over a vast space, of which Kertris perhaps is the 

 centre, you find nothing but pyroxenic lava, along with cones 

 of ashes, beds of scoriae and lapillae. 



I have myself, says M. du Bois, visited the whole of these 

 amphitheatres, which, taken together, are the true key by which 

 to explain those other enigmatical amphitheatres we find filled 

 with fragments of quondam seas, or small Mediterraneans, more 

 or less salt, known under the names of lake Van and Ourmiah, 

 and which have no rivers of egress. The larger of these, the 

 lake Ourmiah, is ^7^ leagues long, by 85 broad, and its surface 

 measures 200 square leagues ; the other, lake Van, is 22^ 

 leagues long, 15 broad, with a surface of 176 square leagues. 



All the volcanic phenomena last described are more recent 

 than the elevation of the Akaltsikhe range, or that of the green- 

 sand. 



But all these fragments of basins, these volcanic uprisings, are 

 nothing more than isolated and partial effects, which were more 

 or less independent of each other. They were but feeble pre- 

 ludes to the last great effect, which was by far the most ex- 

 tensive ; for it has certainly upraised the Caucasus to a much 

 greater height than it previously possessed, and elevated it to 

 the height it now actually reaches, and it was the means of lay- 

 ing bare and dry all those arms of the sea, so to speak, which 

 surrounded it ; in other words, the regions of Colchis, Georgia, 

 Daghestan, and all the vast steppes which so extensively sur- 

 round the Black Sea and the Sea of Azof, and which cover the 

 Crimea. 



Not only did it form a volcanic outburst on the south of 

 the Caucasus, but it gave birth to many volcanic chimneys in 

 the very heart of the chain ; the chief of these vents of eruption 

 are the Elbrous, the Passeinta, Kasbek,the Red mountains, &c. 

 In considering the whole district around the Elbrous, we can- 

 not hesitate therein to recognise the results of an immense crater 

 of eruption and elevation. Trachitic porphyries break forth 

 across black schists, and perhaps likewise through the granites 

 and dioritcs, which we found at the foot of the principal cone. 

 The schists have been raised equally high, and have been over- 

 laid. The Jura system and the analogous formations, surround 



