Physiography of Yarra, etc. 487 



Ijecame more pronounced, the stream in the course of its 

 meanderings would be forced nearer the scarp. 



With the reservations mentioned, the observations now re- 

 corded confirm Prof. Gregory's view that the Yarra is an an- 

 tecedent and a revived stream. 



The broad depression running south through Croydon and 

 Dandenong suggests at first sight that this may have been the 

 old course of the Yarra, and that another stream (the present 

 Yarra west of the Brushy Creek) worked its way eastward and 

 captured the old river at the mouth of the lirushy Creek. 



There appears, however, to be little doubt from the evidence 

 of the Yering Gorge and the general contour of the country, 

 that such depression is a true Senkungsfeld, and if this be 

 admitted, the argument as to the Yarra having originally run 

 through such depression falls to the ground, because such argu- 

 ment is naturally based on the assumption that such depres- 

 sion is river-made. 



An interesting conjecture may be made as to what would 

 have happened had the uplift of the ^'illumbik Peneplain been 

 rapid instead of gradual, and if at the same time such uplift 

 had the same differential characters. The ridges forming the 

 Senkungsfeld descend from Croydon and Lilydale to the north ; 

 and therefore a considerable lake would have been formed until 

 drained through at the lowest point of the basin. The slow 

 uplift however prevented the formation of a lake. 



It may be pointed out that Prof. Gregory does not refer to 

 the Yering Gorge. He remarks that the river turns off into 

 the hilly country known as the Christmas Hills, and flows in 

 a deep gorge through them to the" plains near the Plenty 

 River. This is evidently the Warrandyte Gorge. Had he ob- 

 served the former gorge, it seems certain from its strong con- 

 firmation of his views that he would have cited it. It is how- 

 ever easily missed, imless the river be actuallv followed. 

 Looked at from a distance — e.g., from near the Brushy Creek 

 mouth — the river seems to flow uninterruptedly through low 

 flats and ridges, bounded on its right side by the apparently 

 unbroken Yarra Fault Scarp. 



In passing, attention may be drawn to the fact that al- 

 though comparatively little known, the Warrandyte Gorge 



