J 8 Proceedings of the Royal Soviet n nf Victoria. 



to the Antarctic Circle at South Victoria. The volcanoes in 

 Kanischatka, in the Aleutian Islands, in the Kuriles, and 

 in the Islands of Japan are on this band. I'he second band 

 starts I'roni near the last in tlie neighbourhood of" Behring's 

 Straits, and stretches along the westein coast of the American 

 continent. It is about 8000 miles in length. The third 

 forms a lidge running through the Athmtic Ocean, and 

 divides it longitudinally into two basins. This last chain 

 appears to be verging on extinction, as the number of extinct 

 volcanoes is greater than the active ones, and partial 

 submergence has taken place. 



With regard to volcanic phenomena, the two great factors 

 which have to be accounted for are the presence of highly 

 heated rock masses within the earth's crust, and the existence 

 of various vapours and gases in a state of most intimate 

 mechanical but not chemical union wdth them. (See Judd 

 oil VolcaQioes, page 360.) The active phenomena of vol- 

 canoes must be referred to the presence ot these gases and 

 vapoin-s. 



It niciy be remarked that the theory advanced explains 

 the linear arranpement of volcanoes, the cause of the intense 

 heat, and the presence of vapours and gases in the earth's 

 interior, without assuming it to be other than a rigid 

 mass. 



In investigating the changes and movements which the 

 earth's crust has been sidtjected to throughout geological 

 time, we must considei' the action of two forces. Loss of 

 heat through radiation into space is continually going on 

 from the extei'nal portions of the globe. This is accompanied 

 by contraction. On the other hand, access of heat by the 

 materials far down in the interior would give rise to an 

 expanding or explosive force. The extent of this force would 

 depend on the amount of volatile materials among the 

 substances in the earth's interior, the rate of conduction of 

 heat to them, and the resistance to be ovei'come. In early 

 geological times subteri-anean action, or rather its effects, may 

 have been less because the crust was not so thick, and the 

 resistance to be overcome would have been less. This may 

 account for the enormous times occupied during the 

 deposition of some of the older formations and the greater 

 uniformity observed among their rocks. If the resistance to 

 be overcome was great the forces would accumulate, but they 

 must at some period find an outlet. The phenomena in 



