Mesozoic llochs . 
73 
Whether they do underlie these areas or not does not alter the 
fact that between the completion of the Upper Devonian forma- 
tions (the Avon Sandstones, Iguana Creek and Mount Tambo 
beds), and the commencement of the Mesozoic beds of South 
Gippsland, Cape Otway, and the Wannon, a vast interval of time 
elapsed, during which the Carboniferous rocks of New South 
Wales were beiug formed. If rocks of the latter group were 
deposited in Victoria during that period, a further space of time 
•was occupied in subsequently removing them ; but if such strata 
were not laid down in Victoria, it can only be assumed that the 
period during which they were being formed in New South Wales 
was occupied solely in the denudation and removal of previously 
formed rocks in Victoria. 
Whatever may have been the nature of the changes which took 
place in the interval, it is very evident that there is a great 
stratigraphical break between the Upper Palaeozoic and Mesozoic 
rocks of Victoria. 
Mesozoic Pocks. 
The Bacchus Marsh Sandstones . 
In Mr. A. R. C. Selwyn’s work of 1866, the Bacchus Marsh 
and Grampian Sandstones arc classed as Upper Palaeozoic, though 
the opinion is expressed that they may be younger than the Upper 
Paleozoic rocks of the eastern district. 
The Bacchus Marsh Sandstones, however, yield fossil plants, 
which Professor McCoy regards as of a Triassic or Lower 
Mesozoic type, and I feel justified in separating them from the 
Avon River and Iguana Creek beds of Gippsland, the fossil flora 
of which has an Upper Palaeozoic aspect. At the same time, the 
characteristic fossil plants of the Bacchus Marsh group have not 
been found in the rocks of the other Victorian Mesozoic areas, 
nor have the fossils common in the latter been found in the 
former, and on this account the Bacchus Marsh beds are classed 
separately from those of Western Port and Cape Otway. The 
Bacchus Marsh Sandstones occur between the Werribee and Ler- 
derderg Rivers, a short distance above their confluence at Bacchus 
Marsh." and extend in disconnected areas, much covered by vol- 
canic layers, up the Werribee valley, as far as Greendale and 
Ballatw They consist principally of coarse to fine whitish and 
yellowish brown sandstones of variable degrees of hardness ; 
the lower beds of the series, resting on the Silurian, in many 
places consist of conglomerates. Outliers of conglomerate also 
occur capping spurs oil either slope of the Silurian range 
separating the Lerderderg and Werribee Rivers. At Dailey, 
a few miles up the Lerderderg from Bacchus Marsh, is a coarse 
unstratified conglomerate, consisting of a soft, earthy base, which 
