57 



ones sometimes hollow inside — are found abundantly 

 distributed over the surface of the basaltic plains round 

 Mount Elephant, Mount Eeles, etc.; also, strangely enough, 

 over the tertiary mud plains of the Wimmera, far removed 

 from any known basaltic craters or points of eruption. 

 Small, button-shaped pieces have also been found in the post- 

 pliocene gold drift of Spring Creek, near Daylesford." 



The specific gravity of a Wimmera specimen which was 

 examined by Mr. C. Newbury is given as 2*47, with a silica 

 percentage of 73*7, which definitely identifies it with obsidian. 



How these singular objects found their way to some of the 

 localities in Tasmania, where their occurrence in undisturbed 

 quartz drift far away from any known volcanic source has 

 been reported, is still a mystery. Those which have passed 

 through my hands could not have travelled far with the drift 

 itself, for the long-continued grinding action, which has 

 reduced quartz crystals, topazes, and angular pieces of quartz 

 rock to smooth rounded pebbles, would have been fatal to the 

 preservation of these " buttons," which, though hard enough 

 to withstand ordinary " weathering," are exceedingly brittle. 

 That they had their origin from sub-aerial jets of liquid lava 

 is almost certain, though it may be doubted whether the 

 well-marked, sharp, concentric rings on some of the specimens 

 are entirely due to their rotatory movement while falling from 

 a great height. As to the difference in form of some of the 

 specimens, this would be materially affected by the degree of 

 resistance in the body on which they fell, and by the force of 

 impact. Supposing that they fell while the gravel and 

 shingle drifts were in course of formation, these would be at 

 the bottom of old river channels, under a greater or less 

 depth of water, which would receive them as the drops of 

 lead falling from the top of a shot tower are received in the 

 tank at its base. But some might fall on mud-banks or soft 

 earth, and the spheroidal or button-shaped drop, while in a 

 viscous state, might be drawn out into that ellipsoidal form 

 which has been noticed in some of the specimens. The 

 subsequent accumulation of fresh supplies of drift material 

 might bury these interesting strangers without materially 

 disturbing them ; so that they would appear to be synchronous 

 with the formation of the pebbles themselves. It should be 

 noted that though the "buttons" have often been found in 

 gold or tin bearing drifts, they have no special connection 

 with those particular deposits, and that they are found in 

 them because such drifts are the only ones that are minutely 

 examined by the working miner. 



That the aborigines of Australia are largely responsible for 

 the distribution of the buttons over the mud-plains of 

 Victoria and Eiverina seems highly probable ; but no such 



