176 REACTION OF THE INTERIOR OF THE EARTH 



the south-eastern extremity of the Caucasus between 

 Shemacha, Baku, and Sallian. It is that portion of the 

 great Aralo-Caspian depression in which the ground is 

 most frequently agitated." ( 247 ) When in Northern Asia, 

 I was myself struck by the circumstance that the circle 

 of commotion, or earthquake region, of which the 

 district of Lake Baikal appears to be the centre, extends 

 to the westward only as far as the easternmost part 

 of the. Eussian Altai, as far as the silver mines of 

 Eiddersk, the trachytic rock of Kruglaia Sopka, and 

 the hot springs of Eachmanowka and Arachan, but not 

 to the chain of the Oural. Farther to the south, 

 beyond the parallel of 45 lat., there is found in the 

 chain of the Thian-schan, a zone running east and west, 

 characterised by every kind of manifestation of volcanic 

 activity. Not only does it extend from the " fire-dis- 

 trict " (Ho-tscheu) in Tourfan through the small Asferah 

 chain to Baku, and from thence past Mount Ararat to 

 Asia Minor, but it is even thought that it may be traced 

 between the latitudes of 38 and 40, through the vol- 

 canic basin of the Mediterranean to Lisbon and the 

 Azores. I have treated this important subject of vol- 

 canic geography in detail elsewhere.( 248 ) In Greece also, 

 which has suffered more than any other part of Europe 

 from earthquakes (Curtius, Peloponesos, Bd. i. S. 42 

 46), a countless number of warm springs, either still 

 flowing or which have disappeared, have broken forth 

 during earthquake shocks. A thermic connection of 

 this kind was already pointed out in the remarkable 

 book of John Lydus on earthquakes. (De Ostentis, cap. 

 liv. p. 189, Hase.) The great natural event of the de- 

 struction of Helice and Bura, in Achaia (373 B. c.), 



