1855.] ROSALES GOLD-FIELDS OF VICTORIA, 397 



sometimes curved, and sometimes to the west, as towards Spring 

 Hill, Creswick Creek. 



It is these quartz-veins which form the matrix of the gold. 



Quite unconformable to the slaty rocks is a conglomerate of 

 pebbles of white quartz with a rust-coloured cement. This (the 

 "iron-cement" of the diggers) is the only solidified rock belonging 

 to the alluvial soil, and is found at varying distances, 10 to 20 feet, 

 from the bottom of the alluvium, being sometimes only 1 or 2 feet 

 thick, at others as much as 1 2 feet. 



Where the slate-rock is covered by drift-deposits, it is generally 

 decomposed into silicate of alumina ; but not so much disintegrated 

 as to prevent your distinguishing the "pipe-clay," which has been 

 formed of the clay-slate, from the sandy pipe-clay ("sandstone 

 bottom" of the diggers) resulting from the decomposition of the 

 arenaceo-micaceous slates. Where the strata are decomposed but 

 unmoved, the strike and dip are a sufficient index to distinguish a 

 "true" from a "false bottom," i. e. whether the digger has reached 

 the slate, or has still to penetrate more of the alluvial deposits. For 

 want of observation of this kind, some holes have not been "bot- 

 tomed" at once, whilst one at Bendigo penetrated 200 feet down into 

 the slate in a vain search for another bottom. Although the "pipe- 

 clay" consists principally of silicate of alumina, it retains sufficient 

 potash mechanically mixed with it to render brackish the water 

 which filters through. 



The drift or alluvial deposit sometimes includes two "bearing 

 beds" (charriages), containing gold. The lower of these — beginning 

 from the base of the whole — consists of large quartz-boulders, some- 

 times of 4 or 5 cubic feet volume, which always indicate the run of 

 the auriferous ground ; and these are covered by gravels, sands, and 

 clays, without any regular order of superposition. 



From the absence of basaltic boulders, and from my observation 

 of basalt overlying the auriferous detritus at Clark's Diggings, I con- 

 sider the gold-bearing beds to be older than the eruption and flow of 

 the basalt, although this is followed up by the detrital beds of more 

 recent date. 



Hence results the important fact, that the gold may sometimes be 

 found beneath the igneous rock. 



The alluvial deposits may thus be divided into, — 



T r\ij ^i, V, li. f A. Before the eruption of basalt and 



I. Older than basalt .. < i.i. *< i, • ^^ c\. u i, u 



[ the "charriage ot basalt-boulders. 



f"B. Contemporaneous with charriage of 

 I basalt-boulders. 



II. Newer than basalt. . -^ C. Newer beds covering the basalt- 



I boulders, but older than the forma- 

 (^ tion of the existing valleys. 



At Creswick Creek the "charriage" seems to come from the east 

 and south-east ; but my endeavours to trace it have been foiled in 

 approaching the Ranges, where it splits up into many branches. 

 When thus tracked up, the bed of the charriage shows signs of 



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