482 J. T. Jutsou : 



mouth of the Brushy Creek in the form of a deep, narrow and 

 isolated gorge of the river about a mile in length. Its entrance 

 and its exit are bounded by bi*oad flats. 



This gorge throws a flood of light upon the history of the 

 topography of the country, and I have therefore given it a 

 distinct name — the Yering Gorge. Its significance will be sub- 

 sequently discussed. 



The Mitcham Axis. 



The southern boundary of part of the Yarra Basin may be 

 regarded as a line running from the noi'th of Camberwell to 

 Burt's Hill. This is not strictly correct, as this line has been 

 shown by Mr. Thiele (7, p. 103) to have been breached by the 

 Mullum Mullum Creek. Gardiner's Creek is also an anomaly. 

 The effect of the latter has probably been to divert the waters 

 of Main Creek and adjacent streams to the Yarra instead of 

 directly to the pea. This will be subsequently discussed. For 

 the purposes of the argument the dividing line, as stated 

 above, may be accepted. 



This line keeps fairly close to the Lilydale railway line from 

 Camberwell to Mitcham, and then runs more to the north in a 

 north-easterly direction. 



Between Croydon and Lilydale the water-parting between 

 the Yarra and the Dandenong Creek Basins is more irregular, 

 and it loses something of the ridge-like character indicative of 

 the western portion. The low ridges nowever about Croydon 

 and Mooroolbark appear to have northerly and southerly slopes 

 as if the dividing line were originally continued between these 

 places. All the drainage to the north and east of Lilydale 

 enters the Yarra. 



The country along the line between Camberwell and Burt's 

 Hill gradually rises. About a mile north of the Canterbury 

 railway station it is 380 feet, at the Surrey Hills reservoir it is 

 420 feet, and at Mitcham over 500 feet above sea level. At 

 Burt's Hill — i.e.. on the Yarra Plateau, at the base of this hill 

 — it is by aneroid determination about 560 feet above sea 

 level. It is convenient to refer to this line as the Mitcham 

 Axis. 



