478 ./. T. JiUson: 



This peneplain rises gradually to the north and east from 

 sea-level to varying heights, in its central portions being from 

 iOO feet to 700 feet in elevation, according to its position in 

 the area. 



The peneplain as here defined is apparently that referred 

 to by Prof. Skeats (3, p. 189) as formed at a level of only a 

 few hundred feet above sea level. He regards this peneplain 

 as being formed through the softer sediments being easily base 

 levelled, and the more resistant dacites preserving remnants of 

 an older peneplain, to which he also refers. 



The Nillumbik Peneplain seems to die out to the east about 

 the Steel's Creek country, and pass into that of an earlier cycle 

 of erosion, to which, as previously noted under the description 

 of the Yarra Plateau, the valley of the Yarra east of War- 

 burton also belongs. Until more observations are made, how- 

 ever, the possibility of faulting along some of the boundaries 

 of the Nillumbik Peneplain and the higher lands (for example 

 at Bear's Sugar Loaf) cannot be altogether excluded. This, 

 however, would not affect the character of the Nillumbik Pene- 

 plain, which is a true river-made plain, but would affect the 

 amount of vertical denudation between the present Nillumbik 

 Peneplain and the high land by which it is bounded. 



The Faults and Fault-Scarps. 



Tavo strongly-marked faults have been definitely traced. 



The first — named the Brushy Creek Fault — forms part of 

 the western boundary of the Croydon Senkungsfeld. It com- 

 mences at about the Dandenong Creek to the west of Bays- 

 water railway station, and runs north-eastward to the west of 

 Croydon railway station as far as Burt's Hill ; thence a little 

 to the west of north, forming the western side of the Brushy 

 Creek valley, to the Yarra River at the mouth of the former 

 stream. This fault is about eight miles in length, and 

 forms a prominent scarp in the landscape. It is worthy of ob- 

 servation that it follows the strike of the silurian rocks, which 

 here on the west are in pai't somewhat quartzitic sandstones. 

 The nature of the silurian rocks immediately to the east has 

 not yet been determined, but possibly the earth found relief 



I 



