488 J. T. J at son: 



possesses some of the most beautiful scenery along the Yarra. 

 It has a magnificent series of great bends (of which Pound 

 Bend at Warrandyte is the largest and most impressive), as 

 well as imposing cliffs, long quiet reaches and numerous 

 rapids. Abundant vegetation also fringes the river. 



It might be argued that the Croydon Senkungsfeld is due 

 to direct subsidence, and not to differential uplift. This would 

 imply uplift of the Nillumbik Peneplain as a whole, and then 

 subsidence of the Senkungsfeld. This subsidence, if folloAving 

 closely on the uplift, must have been extremely slow — so slow 

 in fact that the Yarra could erode the Yering Gorge, although 

 the latter is in the higher country. Had subsidence been 

 faster than the river erosion, the stream must have been de- 

 flected to the lower country, and the Yering Gorge Avould not bo 

 in existence. That the uplift was also slow i.s evidenced by the 

 great bends of the Yarra in the Warrandyte Gorge. 



Moreover, if subsidence occurred, it would not be expected 

 that a series of ridges and valleys (although of little respective 

 height and depth), such as are found in the Senkungsfeld, would 

 be formed ; but rather that an even floor on which alluvium 

 would accumulate, would result. 



Another view might be that the whole country was evenly 

 uplifted, that the Yarra cut a young valley similar to the 

 Warrandyte Gorge, throughout its length, and that a recent 

 rapid subsidence is responsible for the Senkungsfeld. From 

 this standpoint, the river-bottom (outside the Yering and 

 Warrandyte Gorges) w^ould be nuich below that of these 

 gorges ; a long, narrow winding lake would be formed, and the 

 drainage would be altered. No evidence of the lake, or of its 

 filling up, or of the diversion of the drainage, has been ob- 

 tained, and so this view may be dismissed. 



Taking the points mentioned into consideration, and also 

 that direct subsidence means two distinct movements — the up- 

 lift of the peneplain as a whole and the subsequent depression 

 of a part — for which there is no evidence ; also that both 

 movements would be very slow ; and also that the one differen- 

 tial uplift meets all the facts of the case, there seems no reason 

 to introduce a second movement, and, therefore, in this paper, 

 the one movement — differential uplift — is adopted. 



i 



