232 Charles Fenner: 



There are paints along the face of the Greendale scarp where 

 the evidence would seem to favour a more recent age than that 

 assigned in this paper, as far as the recession of the scarp face 

 by erosion is concerned. Likewise there are places along the 

 Bacchus Marsh scarp where erosion is so far advanced as to sug- 

 gest a greater age than is here given. Many other similar anoma- 

 lies were noted, pointing to the impossibility of making correct 

 calculations as to relative age purely on the physiographic appear- 

 ance of limited areas. 



That the Greendale fault was post perrao-carboniferous and post 

 older-basaltic is clear from the geological plan (Fig. 8), and sections 

 (Fig. 9 a, b and c), . There cannot' be any doubt that subsequent to 

 the fault some glacial and older basalt remained on the higher 

 block, and have since been almost entirely destroyed. Scattered 

 striated pebbles were found on the crests of the ranges, as were 

 small patches of glacial conglomerate previously referred to. The 

 w^riter also came across an area of scattered basaltic boulders mark- 

 ing the truncated neck of what was probably an older volcano; this- 

 was high up on the Ordovician peneplain to the north of Greendale- 

 and has been mapped. 



The road that passed Mt. Steiglitz proceeds on to the north 

 towards Blakeville along a tongue of basalt. This is undoubtedl}' 

 newer volcanic, though coloured as older basalt in some geological 

 maps. The depth and maturity of the valley so filled by basalt is 

 abundant proof that the fault is much older than the newer vol- 

 canic flow^ which fills it. It may possibly be correlated in age with' 

 the first great period of uplift of New South Wales geologists (ref. 

 48), but is here plainly subsequent to the older basaltic lavas. 



(iii.) Minor Faults. — Several other faults occur in the Werribee 

 River area, but these were not so minutely examined as the two 

 main ones already- described. They will be dealt with as under : — 



^a. Fault bounding the southern edge of Block D. 



„ ,, > b. Fault bounding the southern edge of the Ballan 

 More extensive faults < n j 



) sunkland. 



^-c The Steiglitz Fault. 



d. The Coimadai fault. 

 Less extensive faults \ e. The Bald Hill faults. 



5: 



(. f . Other small faults. 



(a) Fault bounding the southern edge of block D (see e. Fig. 5). 

 The evidence in this case is largely physiographic, since, as will be- 

 seen from the geological map, the higher Ordovician block is more 

 dissected and largely covered by newer volcanic cones and flows,. 



