Physiography of Werrihee Area. 



275 



iis one stands at tlie source and looks down stream, the li-ver 

 is seen to pass into a wide, deep, thickly-timbered, uninhabited 

 valley carved out in the Oidovician rocks of the uplifted peneplain. 

 As before stated, the Lerderderg, down to the point where it crosses 

 the Rowsley Fault, is an old river rejuvenated; one may detect a 

 valley-in-valley structure at various points, and there seems no* 

 doubt that this river was one of those that in early to middle ter- 

 tiary times completed an erosion cycle by the formation of the 

 peneplain. The Lerderderg here receives tributaries from the 

 south and north, and the valley appears quite b^isin-like, narrow- 

 ing in as it rounds the southern side of Mt. Wilson — an important 

 residual range. The river then flows east and south-east through 

 the mining township of Blackwood. Terraces of aurifei'ous allu- 



Flg. 28. — Plan showing probable captures from the Lerderderg River. 

 The thick, broken lines represent prominent Fault Scarps. Tri- 

 butaries of the Korkuperrimul and Goodman's Creeks, working 

 bacb from these scarps, have entirely robbed th? Lerderderg 

 here. Within the triangle formed by the fault scarps, the rocks 

 are hard ordovician slates, through which the Lerderderg flows. 

 The part marked with crosses represents basaltic Hows. 



