Physiography of Werrihee Area, 229 



by Fig. 9 (b). To the nortli rise the high Ordovician ranges, and in 

 the creek-bed the upturned edges of these hard Ordovician slates are 

 cut off sharply by a large east-west dyke. Immediately south of this 

 dyke, the glacial (permo-carboniferous) sandstones occur. In a 

 quarry a few hundred yards further south the same series is seen 

 to be tilted to the north-west, and thus they must be butting 

 directly against the Ordovician, a fact only capable of explanation 

 by assuming a fault of a fairly extensive throw, probably 1000 feet. 

 To the east of this point, small residual ridges, butting against the 

 base of the Ordovician scarp, were dug into, and proved likewise to 

 be Permo-carboniferous. 



Further west, where the Korjamumnip Creek turns east for a 

 short distance along the basei O'f the scarp, we get the section shown 

 in Fig. 9 (a). Here older basalt, undoubtedly resting on glacial 

 sandstones, has been let down against the Ordovician. A visit 

 to this point in the field provides excellent " fault evidence," 

 both geological and physiographical. One stands on a low area of 

 decomposed older basalt, cut off sharply along its northern boun- 

 dary by Ordovician rocks; the latter are cut clean across the 

 strike, and now rise above the observer in steep triangular-faced 

 spurs, rock-strewn, and clothed with timber and bracken. Thick 

 deposits of " scarp-base alluvials " lie on the older basalt a little 

 to the east, and on the west the effect of the fault is further seen Id 

 the deflection of the creeks. 



Further west, a tongue of newer volcanic passes, undisturbed, 

 across the fault line; a series of bores put through this flow close 

 to the line of the scarp gave the following results (ref . 40) : — The 

 newer volcanic, was proved by the first two bores recorded to be 

 somewhat less than 200 feet deep, and of course underlain by river 

 gravels. No. 3 bore, however, passed through 757 feet of basaltic 

 rock without reaching bottom; either the older volcanics are 

 developed to a great thickness close against the scarp, or else the 

 bore came upon the wide dyke (referred to above) which is known 

 to mark the boundary of the scarp for some distance; in either case 

 the bore provides good confirmatory evidencqi in favour of a fault. 



Further still to the west, the scarp may be clearly seen, but the 

 development of newer-basalt flows on an extensive scale somewhat 

 complicates matters. While it is quite possible that permo-car- 

 boniferous occurs on the flat ground south of Frichot's house, this 

 has not been proved. The general higher Ordovician, however, 

 continues on past the south of Bald or Larkin's Hill, and then on to 

 the northward of Egan's Hill. It is very significant that no ter- 



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