270 Charles Fennev : 



from a consideration of the above facts that the site for a storage 

 reservoir in this area was selected on Pyke's Creek. From a con- 

 sideration of Plate XI IB we can ako see how it has been possible 

 for a tunnel to be dug, almost normal to the course of the Werribee, 

 to lead its waters through the intervening higher area, into the 

 Pyke's Creek Reservoir. When we come to consider the grades of 

 the streams as a whole, we find remarkably fine evidence of the 

 uplift and rejuvenation which have already been shown to have 

 markedly affected the topography of the Werribee area. For pur- 

 poses of comparison the profile of a rejuvenated stream (Lockajong 

 River, N.J., U.S.A.), has been re-drawn from ref. 10 to the same 

 scale as used for the Werribee (see Fig. 25). We see in this Locka- 



500- 



Scale, i I I I Miles. 



Fig. 25. — ^Profile of a rejuvenated stream. Lockajong River, N.J., 

 U.S.A. (from Chamberlain and SaHsbury) for comparison with 

 the profiles shown in Plate XIIB. » 



jong river gradient that the characteristics of rejuvenation are 

 shown by a gentle grade, a-b, a steeper grade, b-c (with gorges), 

 and then once more a flatter grade from c onAvard. 



This type of curve is strikingly shown in every river on Plate 

 XIIA, with certain variations, which would naturally be expected, 

 and which will be dealt with. In the lower reaches of the river 

 a few snail streams have been plotted. These flow over the vol- 

 canic pl&in, and then descend somewhat sharply into the steep gorge 

 cut by the Werribee through those plains. 



(iii.) Details of the irulividual Streams. 



(a) The Werribee. — This river is about 71 miles long. Its 

 source lies on the Main Divide, near Mossop's Hill, Old Bullarto, 

 and has been described. The course here lies -in Ordovician rocks, 

 and rapidly deepens. It is here mainly occupying an old valley 

 that had been partly filled by a volcanic flow, but of Avhich only 

 remnants now remain. The gravels below these patches of basalt 

 have been worked for alluvial gold. Musk Creek and Spargo Creek 

 enter the river in steep-sided gullies from the east. 



