34 RIVER YARRA, VICTORIA 
THE MITCHAM Axıs 
Jutson (1911) gave this name to an east-west ridge running 
from north of Camberwell to Croydon. It is the divide between 
the Yarra river system and the streams to the south. Jutson 
claimed that this ridge is a warp axis, but admits that there is no 
evidence of this in the strike of the country rock. He depends on 
the difference in the slopes north and south of the axis, but this is 
due to the relative strengths of the streams on the two sides of 
the divide. If there were any recognizable late Tertiary warping, 
it would show in the deformation of the Nillumbik Peneplain. 
The Mitcham Axis or Ridge is a feature of the present erosion 
cycle, and is due to back-cutting of streams from the rejuvenated 
Yarra (Le., rejuvenated relative to the Nillumbik Peneplain) to 
the north, and streams entering Port Phillip to the south-west. 
THE Mount WAVERLEY RIDGE 
An equally large and important ridge or divide runs from 
Mitcham to Mount Waverley, with a branch running down 
through Glen Waverley to Wheeler’s Hill (Fig. 6). The ridge is 
flat-topped, and averages about a mile wide. The flat top is part 
of the Nillumbik Peneplain, recently bared by the stripping away 
of the Red Beds. Remnants of the Red Beds are still to be seen 
in places as a thin veneer of gravel. The Mount Waverley ridge 
constitutes the western border of the large Dandenong Creek 
physiographic basin, which was carved out of the Nillumbik 
Peneplain. 
If the main Mount Waverley ridge is projected, the line extends 
through Oakleigh to Highett and Black Rock. This is a well- 
marked ridge of high country, as is seen by following the 100 ft. 
and 150 ft. contours on the military map (Ringwood Sheet). 'The 
map also shows how this ridge constitutes a divide. It was called 
the Cheltenham Axis by Hart (1913). 
EARLY TERTIARY DIVIDES 
Since Oligocene times, the Older and Newer Basalts have been 
the chief physiographic determinants in south-central Victoria. 
Before that time the granites and granodiorites (or rather, as 
Mr. R. A. Keble has pointed out to me, the metamorphosed rocks 
around them), along with the Upper Devonian volcanic suites, 
were the chief physiographic determinants. When these are 
plotted on a map they are seen, on the whole, to trace out the 
divides. The actual courses of the pre-Older Basalt rivers can be 
