Prof. John Milne — A Cruise among the Kurile Islands. 347 



volcanos of the Kurile chain with those of Kamtschatka lying to the 

 north, or those of Japan to the south, we shall find that these 

 volcanos of the older countries, Kamtschatka and Japan, as land 

 formers, have done greater work, and i*aised up higher mounds above 

 the level of the sea than anything we find in the Kuriles. 



At first sight this would seem to indicate that the forces which are 

 driving up material through these vents were waning in their 

 powers, and that when mountains like Klutchewsk (16,500 feet) in 

 Kamtschatka, or Fujiyama in Japan (12,365 feet), were raised, the 

 volcanic energy of the West Pacific was greater than when the 

 smaller mountains of the Kuriles, whose elevation perhaps does not 

 exceed 6,000 feet, were uplifted. First it must be observed that I 

 have here compared the mountains of the Kuriles with mountains 

 whose formation was probably contemporaneous ; and secondly 

 that these latter mountains were commenced to be built up from 

 a land surface, whilst those of the Kuriles probably were built up 

 from the bottom of an ocean which is perhaps the deepest in the 

 world. 1 



Looked at in this way, although the Kuriles may not have done 

 so much as the more recent mountains of the groups lying to the 

 north and south of them in adding to the land surface of the globe, 

 they may represent vents from which as much material has been 

 ejected, and this by forces just as powerful as any of more ancient 

 date. 



From the few specimens I collected, the rocks which have been 

 erupted appear to be augitic andesites. These rocks are similar to 

 those in Kamtschatka, Japan, Java, New Zealand, those described 

 by Prof. Zirkel as characteristic of a large area in the 40th parallel, 

 many in Hungary, and, in fact, they have a character iu common 

 with many volcanic rocks of recent origin, which have been collected 

 in many parts of the world. 



That we should find the same character of rock breaking out at 

 so many points, and these in many cases along the same volcanic 

 line, is extremely interesting. 



In reading the description of the several islands, it must be 

 observed that mention of streams of lava has been omitted. The 

 absence of lava streams, as compared with the number you find in 

 a country like Iceland, is very striking, and at the same time 

 suggestive of the way in which these islands have been built up. 



From the small number of mountains which are still giving off 

 steam, as compared with those which are apparently quite extinct, 

 it would seem that the activity of the Kurile chain is fast becoming 

 spent. Why a volcano should become extinct is an interesting 

 speculation. Probably it is that by giving off vapours its energy is 

 becoming exhausted. Another suggestion would be that, by building 

 up cones of such a height, it has gradually destroyed itself by its 

 own increasing hydrostatic pressure. If this were the cause, we 

 should expect to find that when the forces were no longer strong 



1 The soundings made by the Challenger gave for one of the depths to the east of 

 the Kuriles 27,930 feet— the deepest sounding in the Pacific. 



