16 
Geology and Physical Geography ; 
(here however, the recent deposits rest very thinly on Mesozoic 
rocks) ; from Corner Inlet to the Gippsland Lakes ; the country 
bordering the latter on the north, and that extending eastward 
along the coast nearly to Cape Howe. 4th. The areas on which 
the Newer and the Older Tertiary volcanic rocks form the preva- 
lent surface formation. Of the Newer Volcanic areas the principal 
is that lying westward of the meridian of Melbourne, bounded on 
the south partly by the Port Phillip coast and partly by the 
sedimentary Tertiary and Mesozoic areas lying southward of a line 
from Geelong to Portland; on the west, by a lino from Portland 
to the Wannou; and on the north by the Palaeozoic rocks of the 
spurs from the Main Divide. Between some of its leading spurs, 
strips of volcanic rock extend up to, and in some places over, the 
Main Divide, thus connecting the great volcanic areas lying to 
the south with those of lesser extent on the slopes towards the 
Murray. 
Older Volcanic rocks of the Middle Tertiary period constitute 
the surface formation of various small areas in the Geelong district, 
around Melbourne, near Bacchus Marsh, Ballan, and between 
Lothbridge and Steiglitz ; but they aro more extensively developed 
in, or on either side of, the low-lying country which extends 
between Western Port and the La Trobe valley in Gippsland, and 
they also constitute the elevated plateaux known as the Dargo 
and Bogong High Plains. The low ridge near Drouin, previously 
described as forming the connexion between the mountain systems 
of the Main Divide and the South Gippsland Ranges, consists of 
decomposed Older Volcanic rock. 
Throughout the colony, Tertiary sedimentary and volcanic 
cappings and outliers overlie the Mesozoic ami Paleozoic rocks 
up to elevations of nearly 6,000 feet above sea-level. Tertiary 
deposits of marine origin are, howover, only found below an 
altitude of 1,000 feet above the sea; any Tertiary deposits above 
that level show evidence of being due to iluviatile or lacustrine 
agencies, at any rate so far ns the existing arrangement of their 
materials is concerned. 
Having so far given a general description of the main geological 
features, as related to the physical geography of Victoria, the for- 
mations themselves will now be described in ascending sequence, 
so as to portray, if possible, the natural operations and changes 
that have taken place from Palnsozoic times to the present. 
