402 M. F. du Bois on the Geological Phenomena of the 



with their great solid masses the hollow of the crater of eleva- 

 tion ; and the chalky schists, the green-sand, the white chalk, 

 and the whole lower ranges above the Jura system, present all 

 their strata ascending towards the central cone, with an inclina- 

 tion always increasing the nearer they approximate to the foot 

 of the cone. 



But that which best of all, by its lava, characterizes the vol- 

 cano of eruption, forms that portion of the Red Mountains 

 which overlooks the village of Kachaour, upon the great road 

 between Tiflis and Wladikavkas. Two or three cones are raised 

 up against an enormous wall of black schist, which is elevated 

 9000 or 10,000 feet, and whose strata have been so arranged that 

 they present their outgoing to the cones, over which they pre- 

 dominate. Currents of lava have filled up, to a great extent, 

 the large crevice, or more properly, the valley at the bottom of 

 which the Aragri flows. 



During the wHale' of. the tertiary epoch, injections of mela- 

 pyre, and other pyroxenous porphyries, have never ceased to 

 occur in the depression of Colchis and of Georgia, between the 

 volcanos of the Caucasus, and those of Armenia. A great 

 number may readily be observed over the whole of the ancient 

 Colchis, in Karhtilinia, 4-c. ; some of these belong to the era of 

 the upper chalk, but the greater number are as late as the ter- 

 tiary epoch. They explain how the different formations of the 

 tertiary system may be found at heights so greatly different, and 

 in circumstances, as it regards position and derangement, which 

 is only to be explained by their concurrence. We may now dis- 

 cover strata of the upper tertiary, at Bagdad upon the slopes of 

 the Akaltsikhe mountains towards Colchis at a height of 1500 

 or 2000 feet ; and upon the opposite slopes of the Caucasus at 

 Tchekouhi, in the valley of Phase, a somewhat older formation 

 is elevated as much as 3000 and 3500 feet. Between Jor and 

 Alazan in Georgia, the upper formations attain a height of more 

 than 2000. A hundred examples of this sort might easily be 

 cited. 



Such is a summary, concludes M. du Bois, of the history of 

 the land which the last revolution of the globe elevated, and 

 laid bare, free from water, as it now exists. A question here 

 occurs, have the volcanic phenomena ceased now "^ and in an- 



