Caucasian Chain. 537 
No country is more entitled to the name of metamorphic than the 
Caucasus, for M. Dubois proves, that the oldest sedimentary rocks of 
which it is composed, are scarcely of higher antiquity than the Lias; 
whilst Ararat, in great part of recent volcanic origin, exhibits on its 
flanks streams of lava, which must have flowed since the land has 
assumed its present configuration. So modern is this mountain in 
the records of the geologist—so venerable as the cradle of the human 
race. ' 
Let us however cast a rapid glance over some of the chief results 
of M. Dubois’s researches. The central ridges of this mighty chain, ° 
formerly supposed to be of primary age, are nothing more than beds 
of Lias and other strata of the Jurassic age, often so highly altered 
as to resemble ancient slaty rocks, and occasionally pierced by points 
of granite and greenstone. These grand and strangely changed strata 
of the Oolitic series are flanked by huge buttresses of the Cretaceous 
system, some members of which take the form of fucoid schists 
and greensand, whilst others are pure white chalk. Often, indeed, 
assuming ancient lithological aspects, and broken into striking de- 
files, covered by beauteous forests, the far-famed Circassia, from one 
end to the other, is simply the representative, on a grand scale, of our 
English North and South Downs, with their fringes of greensands*. 
Theexplanation of the violent disturbances to which these cretaceous 
rocks have been subjected, is seen in numerous points of porphyry 
and other igneous rocks; by which agents, the strata, altered and 
thrown into highly inclined positions, have been raised to heights of 
10,000 feet above the sea. On each side of the flanks of these 
gigantic mountains, essentially if not entirely composed of the 
younger secondary rocks, are tertiary basins. To the north 
they range into the desiccated Caspians, which form the southern 
steppes of Russia; and to the south they lie inclosed among 
numerous ridges of plutonic and igneous rocks. Volcanic agency, 
of the same extinct nature as that with which we are acquainted 
in Central France, and with which English geologists are now 
familiar in Asia Minor, from the descriptions of our asso- 
ciates Hamilton and Strickland, abounds indeed throughout many 
parts of this region. Of the different phases of eruption, the por- 
phyry cone, the crater and the coulée are the evidences; whilst 
the continued existence of the latent and repressed fires of an- 
tiquity is traceable in the naphtha springs of the adjacent lower 
countries, which are still in action, upon lines running from north- 
west to south-east, or parallel to the grand line of eruption on which 
the Caucasus has been upheaved. M. Dubois distinetly marks the 
great period of elevation of these tracts, when the ridges on the south 
of the chain began to be the centres of many distinct volcanic vents ; 
and when, by the higher and lesser elevations of districts formerly 
submarine, the various “amphitheatres” in Georgia and Armenia 
were formed, all of which he has personally visited. his is truly 
* The botanist will find a striking analogy between the vegetation of the 
western flanks of the Caucasus and the North Downs (Box Hill) in their 
respective groves of Bucus. 
Phil, Mag. S. 3. No. 148. Suppl, Vol. 22. 20 
