Older Volcanic Rocks. 
93 
much greater than now. The areas we now see occupied by 
them are for the most part disconnected vestiges of what were 
once long, continuous, and frequently also widespread sheets 
which have been cut into and through by subsequent denuding 
agencies, so that, in many places, the Older Volcanic rocks, which 
at the time they were poured forth as lavas, flowed down and 
partly filled in the valleys of the period, are now the cappings of 
ranges, owing to the erosion of still deeper valleys on either side. 
Enough still remains to enable some conjectures to be formed as to* 
the areas once occupied by the Older Volcanic rocks ; the conclu- 
sions arrived at will, however, be better understood after the 
existing Older Volcanic areas have been described, and will, there- 
fore, be included in the general sketch history of the Tertiary 
period given in a subsequent chapter. 
Older Volcanic rock occurs in patches, filling hollows in Miocene 
and other older formations in the neighbourhood of the Moorabool 
River, near Maude, and in one place as an intercalated band 
between marine Miocene beds ; it also constitutes a considerable 
area of the Bellariue district, south of Geelong harbor. 
From between Ballan and Blackwood down to near Bacchus 
Marsh the Older Volcanic rock occurs in a number of localities 
especially on the Pcntland Ilills, where some of the liudecomposed , 
basalt of this age is highly magnetic. 
From near Hornsey down to Melbourne there are several ex- 
posures of this rock in beds and banks of creeks that have cut 
their way down to it through newer overlying formations. Near 
Flemington is an area consisting of Oldor Volcanic decomposed 
basalt, which may be seen in natural section on the bank of the 
Saltwater River, passing under Upper Tertiary ferruginous 
deposits, capped with basalt of Newer Volcanic age. From 
Iloddle’s Creek, a branch of the Upper Yarra, a series of discon- 
nected patches, in some places underlaid by auriferous gravels, are 
traceable in the direction of Melbourne, as far as Lilydale. Other 
patches occur between the Yarra and the Plenty, near the 
Kangaroo Ground. This formation occurs again at 13erwick and 
Cranbourne, and lias been proved, by boring operations, to exist 
beneath some 200 feet of Upper Tertiary deposits near Frankston. 
Cape Schanck and portion of the country between Western Port 
and Port Phillip, also Phillip Island and French Island in 
Wostern Port Bay, consist of Older Volcanic rocks in places uiule- 
composed, and consisting of hard dark dense basalt. This rock, 1 
more or less decomposed, occupies a strip extending from Griffith's 
Point along the cast coast of Western Port Bay, and I believe 
this to he portion of and continuous with the French Island and 
Phillip Island layers, and to be united beneath the Newer Tor- 
tiaries with the Older Volcanic rocks which occupy so extensive a 
tract in the Ncerim and Buln Buln district. 
G 
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