158 Baron Humboldt on tlie Mountain-chains and 



by fiery eruptions. Several salt lakes on the two opposite shores 

 of the Caspian Sea have a very elevated temperature ; and blocks 

 of rock-salt, traversed by asphaltum, are formed, as Mr Eich- 

 wald remarks with much shrewdness, " by the effect of a sudden 

 volcanic action, as at Vesuvius,* in the Cordilleras of South 

 America and in Azirbidjan, or even under our own observation 

 by the slow but continued action of heat.'' M. L. de Buch has 

 long directed his attention to the connexion of the volcanic for- 

 ces with the masses of anhydrous rock-salt, which traverse so 

 often and so many formations of horizontal strata. 



We have already seen that the circles of the terrestrial con- 

 vulsions, of which Lake Baikal or the volcanoes of Teen-shan are 

 the centre, do not extend in western Siberia beyond the western 

 declivity of the Altai, and do not pass the Irtish or the meridian 

 of Semipolantinsk. In the chain of the Ural, earthquakes are 

 not felt, nor, notwithstanding the rocks abound in metals, do we 

 find there basalt or olivine, nor trachytes, properly so called, nor 

 mineral springs. The circle of the phenomena of Azerbidajan, 

 which includes the peninsula of Absheron, or the Caucasus, of- 

 ten extends as far as Kizlar and Astrakhan. 



It is the same on the border of the great depression in the west. 

 If we direct our observation from the Caucasian isthmus to the 

 north and north-west, we come to the country of grand forma- 

 tions in horizontal and tertiary strata, which occupy southern 

 Russia and Poland, In this region, the rocks of pyroxene pierce 

 the red free-stone of Yekaterinoslav, whilst asphaltum and 

 springs impregnated with sulphurous gas denote other masses 

 hid under the sedimentary deposits. It may also be mention- 

 ed as an important fact, that in the chain of the Ural, which 

 abounds so much in serpentine and hornblende, and which serves 

 as a boundary between Europe and Asia, a true amygdaloidal 

 formation appear at Griasnushinskaia, towards its southern ex- 

 tremity. 



We shall content ourselves here with observing, with refer- 

 ence to the ingenious opinions recently promulgated by M. Elie 

 de Beaumont, respecting the relative age and the parallelism of 



• In an eruption of this volcano in 1 805, M. Guy Lussac and I found 

 small fragments of rock-salt in the lava as it cooled. My Tartar itineraries 

 likewise speak of rock-salt in the neighbourhood of a volcanic mountain of the 

 Teen-shan, north of Aksou, between the station of Turpa-gad and Mount 

 Arbab. 



