146 



MISS HILDA BOORD^ ON 



action is not truly volcanic because there is no lava. Many of the 

 greatest eruptions that have taken place in the world have been 

 entirely devoid of lava flows. The great eruption of A.D. 79, which 

 destroyed Pompeii and Herculaneum, was entirely without lava, 

 and the recent West Indian eruptions were entirely destitute of 

 lava flows.* These are explosive eruptions in which the whole of 

 the lava has been converted into fragmentary ejectamenta. So 

 that the absence of lava is no indication of want of true volcanic 

 action. 



The fact of these eruptions in New Zealand being chiefly explosive 

 and without lava-flows is due, I think, to the fact that the rocks are 

 chiefly acidic (or siliceous) and to there being a great access of 

 water to the rising lava, and so converting the whole into ejecta- 

 menta of a dry solid character which otherwise, without a sufficient 

 amount of water, would have partly flowed away in liquid lava. 



There are a great many points that are suggestive of remark, but 

 I will not occupy your time further. 



The Chairman. — I think we have a gentleman here who ha& 

 been to the Lipari Islands, Mr. Narlian. 



Mr. Narltan. — AVhat I have seen of the photographs reminds me- 

 very much that all the formations I have seen are very much like 

 what we have had at Nilcano. Again, as the Professor has observed, 

 in all acidic formations there is an absence of lava-flow. The last 

 great eruption we had was absolutely devoid of all lava-flow. The 

 vapour and fumes were highly charged with electricity, and the 

 column ejected might have been 15,000 feet as well as we could 

 measure. Of course it was not all charged with water, but the 

 shaft and small bits perhaps of rock went up, in many cases,. 

 15,000 feet. Estimating the height of the mountain from the level 

 of the sea, and taking the proportion of the column ejected from the 

 crater, I could not take it under that measure. Some of the great 

 boulders ejected were a good deal more than the size of this room, 

 and were ejected to a distance of 1 or IJ miles, and a great 

 many of them have been spread over the island. 



I believe in other cases, also, a terrace-like formation is found. 



* " Volcanic action and the West Indian eruptions of 1892," Trans, 

 Vict. Inst.^ vol. XXXV, p. 214 (1903), also the same subject by Prof. J. W. 

 Spencer, ibid., p. 198. 



