454 SIR RODERICK I. MURCHISON'S ADDRESS. [>Iay 25, 1857- 



and can rarely be followed to any great depth except at a loss in 

 working them. Again, as the richest portions of gold ore have 

 been aggregated near the upper part of the original veinstones, so 

 the heaps of gravel or detritus resulting either from former powerful 

 abrasion or from the diurnal wear and tear of ages, and derived from 

 the surface of such gold-bearing roclvs, are, with rare exceptions, 

 the only materials from which gold has been or can be extracted to 

 great profit. These postulates, on which I have long insisted, in spite 

 of the opposition of theorists and schemers, have every year re- 

 ceived further confirmation, and seem, on the whole, to be so 

 well sustained as matters of fact, that the real problem we have 

 now to solve is. How much time will elapse before the gold of 

 Australia is finally riddled out of these heaps or basins, or extracted 

 from a few superficial veinstones ? 



It would indeed be presumptuous in any one who had not closely 

 surveyed the rich auriferous tract of Victoria to pretend to answer this 

 question ; but I beg my associates to understand, that there is a wide 

 distinction between the measurable capacity of the contents of these 

 broken heaps, or rare thin veinstones in situ, and those imaginary 

 mountains with bowels of gold of the theorist, the very thought of 

 which has shaken the nerves of so many fundholders. For, it must be 

 remembered, that all the accumulations of broken golden materials, 

 or the great sources of supply, have well-defined bottoms. They are, 

 in fact, troughs filled in with gravel or shingle, the cubical contents 

 of which, when the country has been thoroughly surveyed, can be com- 

 puted ; and though it may never be possible to predicate the amount 

 of ore contained in all parts of such slopes or hollows, yet, judging 

 from the rate of excavation now going on, a good geologist like Mr. 

 Selwyn, who is conducting the survey in Victoria, may well be 

 able to give us approximate data as to the probable number of years 

 required to empty out the metalliferous fragments from all those 

 troughs or basins in which they have been detected.* 



The other sources to which I have alluded, I learn from Mr. West- 

 garth, an intelligent resident of the colony, have however of late 

 been worked to some profit. These are the narrow veinstones of 

 quartz rock, two or three feet thick, which at the surface are rich in 



* A certain amount of the gold of Melbourne, whether occurring in drift or finely- 

 levigated clay, is reached by sinking shafts through basaltic coulees, which have 

 evidently flowed in recent times, since they cover woody substances, including 

 cones which, though in a charred or brown-coal condition, have been recognized 

 by Mr. Robert Brown, as belonging to the remarkable Australian living genus, the 

 Banksia, which that great botanist was the first to find and describe. 



