Victoria as a Field for Geologists. 23 



its original form, fluoride of silicon, by giving up the alumina, 

 and re-appropriating the silica to itself This process is 

 repeated many times in passing through the tube, and at last 

 the gas issues from the one end as it entered at the other, 

 fluoride of silicon. 



Here, then, is a metamorphosis not unlike the one re- 

 quired. There are plenty of veins, too, answering to the 

 supposed first condition of the reefs of quartz, and veins 

 general^ referred to igneous action. Such are the elvan 

 dykes, tlie principal constituents of which are, if 1 am not 

 mistaken, silica and potass. There are two of these dykes 

 near the Botanical Gardens, tvvo cross the Moonee Ponds 

 Creek above Flemington, and others are by no means un- 

 common in various parts of the colony. We now want some 

 permeating gas or fluid to remove the foreign substance, so 

 as to leave the quartz in a state of purity. This requirement 

 might, perhaps, be met by high pressure steam or superheated 

 water. The whole, however, is, as I told you, merely 

 suppositious, and you will therefore discuss it or dismiss it 

 as unworthy of notice, as seems most fitting to you. 



Near Bacchus Marsh, in the gorge of the Werribee, rocks 

 are met with which Mr. Daintree classes as upper palseozoic, 

 and speaks of as possible equivalents of the old red sandstone. 

 It is this same series of strata v/liich, in Great Britain, were 

 once thought to be barren of organic remains, but which 

 yielded the Scotch geologist, Hugh Miller, such an abundant 

 harvest of unique forms. It will be interesting to see 

 whether still fresh additions to the ichtholites of the period 

 are to be made by the Victorian beds, and to observe what 

 novel shapes the plericidhys or cephalasois will take Vv'-hen 

 located as denizens of the Antipodes. 



By the Geological Map I see that these same beds are 

 classed as permian, so that it may be supposed their age 

 has been determined by the geological sm-vey. They 

 present, how^ever, another problem of no little interest. Are 

 they, or are they not, auriferous ? Mr. Daintree speaks of 

 them as " seen resting on the upturned edges of the silurian 

 slates and sandstones, with their associated quartz reefs, 

 which do not pass into the overtying conglomerates (i.e., of 

 the permian beds). The drift of the valley has been v/orked 

 for gold, proving the a^uriferous cha.racter of the reefs ; and 

 here we should be able to work out the relative age of the 

 gold." And this question, especially as viewed in connection 

 with the theory of quartz reefs being richest near the surface, 



