RIVER YARRA, VICTORIA 33 
At the close of the Eocene and in Oligocene times, it appears 
that the land gradually sank in relation to the sea, and in wide 
low-lying areas great quantities of lignite accumulated, especially 
in south central Victoria and southern Gippsland (see Fig. 5). 
TEN BROWN COAL DEPOSITS II 
BACCHUS MARSH 
ALTONA BASIN 
Scale of Miles 
FIG. 5 
Map showing extent of lignitic deposits in southern Victoria. The alignment 
of the Bacchus Marsh-Altona basin indicates the direction of early Tertiary 
drainage in that area. 
The sinking was contemporaneous with considerable volcanic 
activity, and the two events may be not unconnected. The relative 
lowering of the land continued so that there was an extensive 
transgression of the former land surface, with deposition of 
Eocene, Oligocene, and Miocene marine beds on what is now 
the land. A number of the basalt flows were in part covered 
with these marine sediments. In this cycle of events the Nillum- 
bik Peneplain was formed, and the Wurunjerri flow of basalt 
extruded upon its eastern extension. 
In Lower Pliocene times the sea began to recede, and the 
rejuvenation of streams brought down copious torrent gravels and 
sands which were spread over the Nillumbik Peneplain to form 
the Red Beds, remains of which are seen as cappings on the hills 
to the north of the peneplain, and as a continuous cover further 
south. Still later, in an arid period, siliceous sand dunes were 
constructed over the Brighton-Sandringham area. They covered 
the Miocene marine deposits and Pliocene fluviatile-marine Red 
Beds. The recognition of the trend lines in the physiography of 
this area as dune lines (Whincup, 1944) explains a number of 
features Hart (1913) found it difficult to account for. 
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