504 J. T. Jutson: 



exposed rocks are fine-grained, tough sandstones, with some 

 quartz veins. With the sandstones are no doubt interbedded 

 shaly rocks. The sandstones in places become almost quartz- 

 ites, and in the narrow north and south belt, comprising Croy- 

 don and Burt's Hills and the " Kopje," the rocks seem some- 

 what more resistant than elsewhere. The greater difficulty in 

 the removal of these hard rocks may therefore account for 

 the monadnocks mentioned. 



The ''Kopje." 



This is an isolated hill on the Nillumbik Peneplain, just west 

 of the Brushy Creek Scarp, and close to the Canterbury-road. 

 It is clearly a monadnock, and it sweeps up to a height of pro- 

 bably nearly 100 feet above the surrounding peneplain as a 

 small but bold cone. 



A most instructive section can be obtained here. Taking a 

 traverse from the west of the " Kopje ' we have first the Nil- 

 lumbik Peneplain, then this monadnock, then the peneplain 

 again for a short distance to the Brushy Creek Fault, where 

 the Nillumbik Peneplain is thrown down about 85 feet. Far- 

 ther east at a lower level again is the alluvial flat, through 

 which a tributary of the Dandenong Creek meanders. Thus 

 there are four distinct levels of country, the explanation of 

 which may be inferred from the earlier part of this paper. 



Kangaroo Ground. 



This high ground is due to a small patch of basalt, which is 

 generally regarded as older basalt. This and that capping the 

 hills at Greensborough will be dealt with in another paper. 



The basalt at Kangaroo Ground rises well above the general 

 peneplain of the sedimentary silurian rocks (the Nillumbik 

 Peneplain) ; such elevation appears to be due to the basalt 

 having been erupted before the formation of the peneplain, 

 and having largely resisted the general planation by reason of 

 its superior hardness. 



The Kangaroo Ground therefore forms a true monadnock, 

 although somewhat dissected. 



