236 Charles Fenner : 



The contrast between the two parts visited, when compared with 

 other similar areas which have been closely examined, strongly 

 suggested an important break between the t^vo, with a let-down to 

 the south. This evidence also fitted in with the fact that from 

 nearly every distant view, a peculiar break was noted in the level 

 summit line of the Brisbane Ranges. All of this was of course in- 

 sufficient evidence on which to assume a fault. The writer has, 

 however, been delighted to discover that an extensive fault hasi been 

 proved to run through south of Steiglitz; it has been located and 

 investigated by Mr. W. H. Ferguson, of the Victorian Geological 

 Survey, and the evidence is of a most striking and complete strati- 

 graphical nature. Mr. Ferguson's report is, unfortunately, so far 

 unpublished, but permission to include the foregoing statement in 

 this paper has been kindly granted by the Mines Department. 



(d) Coimadai Fault. — (See d Fig. 5.) This fault is probably of 

 the same age as that at Greendale. The fault line is short, about 

 five or six miles, and runs east-west with a down-throw to the south. 

 The evidence is both physiographic and geological. The ancient 

 " BuUengarook creek," now filled by the BuUengarook lava stream 

 (ref. 42), flowed across this fault. 



The country to the north is much higher than to the south. On 

 the western side of the BuUengarook lava flow, Back creek flows 

 eastward alongi the fault. On the left bank (north) the Ordovician 

 rises steeply, and on the right bank there is ai large area of glacial 

 ■conglomerate. The boundary line, as mapped by Officer and Hogg 

 (ref. 43) is almost straight, but it does not appear to be referred to 

 by these writers as a fault. They apparently regarded the east- 

 west Ordovician escarpment as a pre-permo-carboniferous feature^ — 

 purely a physiographic impossibility, since the great mass of permo- 

 <'arboniferous glacial rocks, that now lie at a much lower level 

 near the base of the scarp, are accepted as relics of glaciers that 

 flowed in a northerly direction. Hart (ref. 22, p. 257) records his 

 belief that this line would be found to mark a fault. 



On the east of the BuUengarook basalt tongue, the limestones, ter- 

 tiary sands, and glacial beds of Coimadai are on the let-down side 

 of the fault, while the steep " pinch " on the road that runs north 

 from Coimadai to *' The Basin " is really ascending this fault 

 scarp. It is quite likely that differential erosion has accentuated 

 the scarp just here, but the geological relations are conclusive. 



(e) The Bald Hill Faults. — These faults are best seen in the field 

 in sunmier, when the grass is dry, and the soil differences are most 

 apparent. They occur at Bald Hill, north-west of Bacchus Marsh, 



