458 THE GEOLOGY OP THE NEW HEBRIDES, 



Class ii.j dosalane. 

 Order 4, quardofelic, Austrare. 

 Rang 2, domalkalic, Dacase. 

 Subrang 3, sodipotassic, Adamellose. 

 Vit7^ophyri-adamellose . 



Addend a. — The pumiceous variety of this lava is abundantly 

 developed in a fragmentary condition forming thick beds of tuff. 

 In the hand-specimen it closely resembles the white drift pumice 

 of the Pacific, which is now definitely ascertained to be derived 

 from submarine outbursts such, for instance, as are known to 

 have taken place within recent years along the Kermadec 

 Tongan fold-line. Careful estimations of silica in the Havannah 

 Harbour pumice and in a specimen, collected by us in the New 

 Hebrides, of white drift pumice known to have originated from 

 a submarine eruption which took place early in 1903 in the 

 vicinity of Tonga, gave the following results : — 



Hav. Harb. pumice tuti (dried at 100° C.) SiO 2 59-68%. 



Drift pumice from vicinity of Tonga (dried at 100° C.) SiO.^ ... 66*80 %. 



Professor Liversidge has published* analyses of the two 

 varieties of Pacific drift pumice, which are interesting for com- 

 parison. 



• Journ. Free. Roy. Soc. N. S. Wales, xx. 1886, 235. 



