H'i(/l(/(iin/s of Westrrii V'lchirla. 261 



may be at any hei<rht wliitli was sut+icicnt to turn the waters of 

 the adjacent valley. Thus the drainaue oi" the south slope of 

 the Mt. Bolton Ran^e is diverted northward. A Divide is ob- 

 tained which, thou<ih usually ([uite distinct, is yet at a low level, 

 and w-e have a remarkable feature of the levels of the Waubra 

 Railway that it is everywhere at a hit>'her level than close to 

 the Divide, fallinof from 1508 feet at Waubra Junction to 1350 

 at Leitrmonth, then crossino- the Divide at abovit 13G0 and 

 ascendiup- a valley to Waubra. Tliere are i^everal swamps close 

 to the Divide where the slopes of the volcanic hills meet. Lake 

 Learmonth only differs from these swamps in beinjr larger and 

 practically permanent, which has been helped by building up 

 its outlet and lirintrinp' in water across the Divide. 



Beneath the extensive volcanic area both north -west and north- 

 east of Hallarat there is still some uncertainty as to the cour.-es of 

 the old Divide and of the old valleys. We may safely say that 

 the whole area which now drains north also drained north before 

 the lava flows. In the Ercildoun Gap is ai lead falling north ; in 

 the Ascot Gap another lead also falling to the north, and a 

 north falling lead exists not far north of the present Divide at 

 Dean. Bat south of the Divide there are three areas which 

 present difficulties, the Burrunibeet Basin, the western lead>j 

 of Ballarat and the Haddon leads, and the area about Warren- 

 heip and Bnngaree. Investigations have usually proceeded on 

 the assumption of the non-disturbance of relative levels at 

 different points, but we have sufficient evidence that this is not 

 absolutely safe. We must take account of local disturbances^- 

 and of unequal movements affecting large areas, as will be shown 

 below. 



The question is further ciuiiplicatcd liy changes of the tiow of 

 streams by the ordinary process of river capture, and by the fact 

 that various lava .streams which have altered the flow or in- 

 fluenced it are not absolutely, and sometimes not approximately, 

 contemporaneous even within the one drainage area. By this 

 mean* a great change might be produced in one part of a valley 

 while another part of the same valley was unaffected. 



1 Notes on the Stony Creek Hasiii, Daylesford, and references there. Proc. Roy. Soc. 

 Victoria, XVII., pt. II., New Series. 



