THE GEEAT ERUPTION OF SAKUEA-JIMA IN 1914. 119 



poncnts it is liighly probable that the asli materials were derived 

 from trituration of pumice. It is therefore to be classed with 

 magma-glass ash, but not lava ash. 



A question naturally arises : Which vent — the western, Yuno- 

 liira or the eastern, Nabé-yama vent — supplied the major portion 

 of ash materials ? To give a proper answer it is first of all 

 necessary to know tlio date of any ashfall which should have 

 been gathered in a special receptacle, but that precaution was 

 unfortunately not carried out. 



As will be immediately stated in speaking about lapilli, the 

 main ash producers were the eastern vents {see ante, p. 68, footnote), 

 for the reason that the magnetite found possesses well-defined 

 crystal form and glass pure white, while the western vents hurled 

 out only dirty glass particles and magnetite clumps. 



h) The SAND {moyezuna or ' burning sand ') varies in size 

 from 1 to 2 mm., corresponding to the gravel in the above scale, 

 though the one witli 3 mm. is tolerably abundant. Like lapiUi, it 

 is really rock particles, differing from them, however, in its com- 

 pact texture, the color being usually black. Undoubtedly it must 

 have precipitated in a large quantity at the very beginning of the 

 eruption as a rain of sand of old lava, when vents first broke 

 open through a preexisting lava sheet of volcanic body. It has 

 contributed in large measure to the darkness of the cauliflowers^^ 

 (PI. I.) of dust clouds, which gave an awful impression to persons 

 who happened to view the scene from far and near. 



Towards the climax of paroxysm the sand became rarer. 



1) The form produced is similar in principle to the smoke ring of tobacco-smokers. The 

 puffed vip vapor in the air from a volcanic vent expands in the horizontally rotating axis in 

 shaping that curdy salmiacal ring, and the solid particles intermixed in smoke columns are 

 sorted and fall leeward as a black rain of volcanic ash and sand. See A. Sieberg, ' Einführung 

 in die Erdbeben- und VulkankiTnde Süditaliens,' Jena, 1904, S. 203. 



