192 Charles Fenner : 



of 1911, we get an estimate of about 6250 tons of solid carried to- 

 the seal in that year — an average of about 12 tons per square mile. 

 Probably more complete data will show that this estimate is below 

 the truth. 



If we compare these figures with those of the great and actively- 

 eroding rivers in other parts of the world (Russell, " River 

 Development "), we find that the Werribee is not doing very exten- 

 sive eroding work. This is indicated by the following figures, show- 

 ing the proportion between the weight of sediment carried and the 

 weight of water : — . 



Rio Grande, 1 : 291. 



Uraguay, l': 10,000. 



Werribee, 1 : 35,000. 



The figures on which this result is based are reliable, but, un- 

 fortunately, incomplete. In view of the comparatively high grades 

 of the various streams of the Werribee, and the extensive dissection 

 proceeding in the uplifted blocks, clearly shown in Fig. 30, the 

 result seems very low. 



It must be remembered, however, that the rainfall is compara- 

 tively poor, and spread over the greater part of the year. Since a 

 river does most of its erosive work in flood time, and especially at 

 maximum floods, this distribution of the rainfall must be a factor 

 against high erosion. Further, the river is working largely in 

 very resistant rocks — indurated palaeozoic sediments and almost 

 undecomposed basalts. Probably the above ratio would be more 

 comparable to that of streams of the same size, working under 

 similar conditions; no figures for such comparisons were obtain- 

 able by the writer. 



VI. — Introductory Survey of the Area. 



In order to convey a preliminary general idea of the physio- 

 graphic features of the area, we may imagine that we are enabled 

 to take a bird's-eye view of the whole country-side. (c.f. Plate XI.) 

 The general impression would be of an area of low relief, rising 

 from the flat shores of Port Phillip Bay to a general level of about 

 2400 feet at the " Main, Divide " of, Victoria, some 50 miles north- 

 ward. 



Colour differences, due to the contrast between the heavily- 

 timbered and the pastoral areas, would be apparent, and the 

 winding southern and south-easterly rivers would be visible. Along 

 these, narrow deeply cut gorges would be noted, apparently irregu- 



