GENERAL CHARACTER OF THE URAL. 
341 
geological explorer, Count Keyserling, returned to St. Petersburgh (see General 
Map, PI. V.). His survey shows, that forming the western flank of the great valley 
of thePetchora and the eastern limit of the great Permian basin, this ridge, though 
composed of palaeozoic and metamorphic deposits which have been pierced by 
igneous rocks, ought to be dissociated from the Ural in a geological sense, and must 
rather be viewed as the stony girdle of Russia in Europe, which extending from 
Scandinavia on the north-north-west, envelopes and forms the natural mural portion 
of the adjacent European formations. This ridge, whose strata contain organic 
remains which throw great light on the palseozoic fauna of Russia, will be con- 
sidered in a separate chapter. 
The extreme southern limits of the Ural are viewed by Humboldt as extending 
considerably to the south of the parallel of Orenburg, viz. by the mountains 
Mugodjar to Mount Airuk, whilst its extreme southern end is considered by him 
to lie in the higher grounds between the Aral and Caspian Seas. The recent 
discovery of a ridge of eruptive rock to the north of Khivah, to which we have 
before adverted, to say nothing of a better acquaintance with the structure of the 
crystalline chain which trends southwards from Mount Airuk towards the Aral Sea, 
seems even to extend the generalization of Humboldt, and to lead ns to believe 
in a great southern prolongation of igneous and palaeozoic rocks, which, ranging 
into Central Asia, beyond the depression of the Aral, constitutes the high ground 
on the right bank of the Oxus '. In this extended sense, then, a grand meridian 
elevation, of which the Ural Mountains, properly so called, is the distinguishing 
central feature, has a length of nearly 30° of latitude. 
For a knowledge of the north-eastern flank of the chain, extending from 60° 
to 65°, we shall appeal to Russian authorities ; whilst our own acquaintance with 
some features of the western flanks within the same latitudes, enables us, as above 
said, to speak personally of a tract (the Timan ridge) not previously visited by 
any geologist. Our chief observations are, however, restricted to that part of the 
chain which is colonized and accessible ; viz. from Bogoslofsk in 60° to Orsk and 
Orenburg in 51°, or throughout 9° of latitude. 
Within these parallels, the average altitude of the mountains does not exceed 
, Our acquaintance with the structure of the southern prolongation of the Ural, beyond Mount Airuk, 
is due to M. N. Khanikoff, Captain Romanoff, and the researches of M. Basiner obligingly communicated 
to us hv Colonel Helmersen. 
2 Y 
