175 cos;.;os. 



petroleum springs, more distinctly expressed or more clearly 

 recognizable, than in the south-eastern extremity of the 

 Caucasus, between Schemacha, Baku, and Sallian. It is 

 the part of the great Aralo-Caspian basin, in which the earth 

 is most frequently shaken." 23 I was myself struck with the 

 remarkable fact that in Northern Asia the circle of commo- 

 tion, the centre of which appears to be in the vicinity of Lake 

 Baikal, extends westwards only to the eastern borders of 

 the Russian Altai, as far as the silver mines of Riddersk, 

 the trachytic rock of Kruglaia Sopka and the hot springs of 

 Rachmanowka and Arachan, but not to the Ural chain. 

 Further, towards the south, on the other side of the parallel 

 of 45 1ST., in the chain of the Thianschan (Mountains of 

 Heaven) there appears a zone of volcanic activity directed 

 from east to west, with every kind of manifestation. It 

 extends not only from the fire district (Ho-tscheu) in Tur- 

 fan, through the small chain of Asferah to Baku, and thence 

 over Ararat into Asia Minor ; but it is believed that it may 

 be traced, oscillating between the parallels of 38 and 40 J JS ., 

 through the volcanic basin of the Mediterranean as far as 

 Lisbon and the Azores. I have elsewhere 24 treated in detail 



23 At Schemacha (elevation 2393 feet), one of the numerous meteoro- 

 logical stations founded by Prince Worouzow, in the Caucasus, under 

 Abich's directions, 18 earthquakes were recorded by the observer in 

 the journal in 1848 alone. 



24 See Asie Centrale, tome i, pp. 324329, and tome ii, pp. 108 

 120; and especially my Carte des Montagues et Volcans de I'Asie, com- 

 pared with the geognostic maps of the Caucasus, and of the plateau of 

 Armenia by Abich, and the map of Asia Minor (Argaeus) by Peter 

 Tschichatschef, 1853 (Rose, Reise nac/i dem Ural, Altai, und Kaspischem 

 Meere, Bd. ii, pp. 576 and 597). In Asie Centrale we find: "From 

 Tourfan, situated upon the southern slope of the Thianchan, to the 

 Archipelago of the Azores, there are 120 degrees of longitude. This is 

 probably the longest and most regular band of volcanic reactions, oscil- 

 lating slightly between 38 and 40 of latitude, which exists upon the 

 face of the earth ; it greatly surpasses in extent the volcanic band of 

 the Cordillera of the Andes in South America. I insist the more upon 

 this singular line of ridges, of elevations, of fissures, and of propaga- 

 tions of commotions, which comprises a third of the circumference of a' 

 parallel of latitude, because some small accidents of surface, the un- 

 equal elevation and the breadth of the ridges, or linear elevations, a.s 

 well as the interruption caused by the sea-basins (Aralo-Caspian, Medi- 

 terranean, and Atlantic basins), tend to mark the great features 

 of the geological constitution of the globe. (This bold sketch of a 

 i-egnlarly prolonged line of commotion by no means excludes other 



