Fhysiogra/)//!/ of Y((rra, etc. 475 



80 down into the valley of the Yarra. These spurs indicate 

 that this part of the country has escaped the plauation which 

 formed the peneplain, and that such country apparently be- 

 longs to an earlier cycle of erosion than the plateau. 



Belonging also apparently to this eai'lier cycle of erosion 

 is the Yarra valley, east of Warburton. This area and the 

 country mentioned in the last paragraph, have not been suffi- 

 ciently examined to state whether any evidence exists in sup- 

 port of this earlier cycle, such as old valleys trenched by 

 younger ones. 



From the Main Divide to the Yarra, the plateau is bounded 

 on the east by the higher country at Steel's Creek and farther 

 east. The boundary then follows the Yarra to Brushy Creek, 

 thence along the western side of the latter to Burt's Hill, thence 

 south-westerly through the Springvale district to the sea. 

 Its western boundary may be regarded as a line drawn from 

 Mount Disappointment southward to Port Phillip Bay. 



Another part of the plateau is probably most of the Woori 

 Yallock and Hoddle's Creeks Basins. This part is separated 

 from the main area by the depression of the middle Yarra 

 country. Its exact relations with the main part of the plateau 

 have not yet been determined. 



The Croydon Senkungsfeld. 



The Yarra Plateau is tianked in parts by a belt of low coun- 

 try, characterised by wide alluvial flats, low ridges and broad, 

 open valleys, of which those at Yarra Glen and Bayswater may 

 be taken as types. The tops of the ridges indicate that this 

 low belt of country had originally a level surface, and is really 

 a dissected plain. 



Tlie difference of elevation between the Yarra Plateau and 

 this lower country I regard as dtie to unequal uplift, the less 

 raised portion being a true Senkungsfeld, which can con- 

 veniently be referred to as the Croydon Senkungsfeld. Croy- 

 don is situated on the boundary between the Yarra and Dan- 

 denonof Creek Basins, and as the Senkuno^sfeld belongs to 

 both, the name of this township has been adojjted for this 

 depressed belt of country. 



