Obsidian Bombs in Australia. 41 



responsible for their being found at all, for had they become 

 rounded and water-worn they would have passed unnoticed 

 amongst the material comprising the wash. Considering their 

 brittle character^ and the conditions prevailing in transport by 

 water, those which have been so found could not have been 

 transported any distance worthy of mention, and this is consistent 

 with their occurrence in shallow alluvial (post-pliocene), which is 

 generally comprised of comparatively unrolled material derived 

 from the adjacent country. On the other hand, they could 

 scarcely have survived the attrition suffered in the formation of 

 the deep leads, and if they did they would easily escape observa- 

 tion. It is quite evident, therefore, that in this instance the 

 distribution could at the best be only a comparatively limited 

 one, and that they are mostly found at or near the place of 

 original deposition. 



Those occurring on the surface, with the exception of the 

 Charlotte Waters specimens, are similarly free from any signs of 

 attrition, and are mostly in a most perfect condition, although 

 some exhibit slightly weathered surfaces. 



Independent of this, all other features associated with water 

 carriage are entirely wanting, so that rivers or creeks, either of 

 the past or present, cannot have taken any important part in 

 their distribution. 



Icebergs as a distributing agent cannot be considered seriously, 

 as the conditions which would have been assumed are quite out 

 of the question. For instance, we should have to assume that 

 the continent was entirely submerged, over which the icebergs 

 with their loads drifted and there deposited them. We must 

 then suppose that the continent was raised above the watei-, the 

 surface features being much as they are now, and we must 

 further give the icebergs a monopoly of carrying obsidianites 

 only from their origin, which it has been 



1 Mr. J. G. O. Tepper, who translated Stelzner's letter, in a footnote thereto points out, 

 as an objection to volcanic origin, that all molten glasses, lava, slags, etc., if cooled 

 comparatively rapidly in the form of small masses, exhibit great and, mostly, excessi\'e 

 brittleness, which is not the case in the comparatively very small Australian bombs. In 

 fact, they could not have been preserved at all if assumed to have been carried great 

 distances by currents of flowing water and subjected to attrition by violent contact with 

 other rock fragments, if they had not been endowed with a very considerable degree of 

 cohesiveness. 



