110 Charles Fenner: 



winding in a definite channel through a wide, middle-aged valley 

 (see Plate XIX.). In the central tract of the Wannon, up as far as 

 Mount Sturgeon, we have the river taking a most unexpected loop 

 to the north, towards the mountains, and thence wandering slug- 

 gishly and wide, with practically no defined valley, north-west, 

 then west, and south-west, passing over waterfalls into the lower 

 Wannon in the neighbourhood of Tahara. Still further towards the 

 source Ave have Dwyer's Alain Creek and the Upi^er Wannon (above 

 Mt. Sturgeon) flowing almost due south in deep stable valleys in 

 the hard rocks of the Grampians. 



We thus have an upper and a lower tract of more mature age, 

 Avith a central part of extreme youth. As before indicated, there 

 appears to be no doubt that this uppermost part, with Dwyer's 

 3Iain Creek, originally flowed on to the south as a separate river; 

 also that the lower Wannon did not extend nearly so far eastwai-d 

 as at present (see Fig. 3). With the advent of the newer basalt 

 period, however, a great sheet of lava effectually dammed up these 

 present tributaries of the Upper Wannon, in the neighbourhood of 

 Mt. Sturgeon, and forced the streams to slowly find their swarnpy 

 way right round the northern margin of the basalt sheet, finally 

 reaching the Avider and more mature valley of the lower Wannon. 

 Thus, to use the terminology of rivers, the Lower Wannon is a 

 ■"consequent " stream, the extreme Upper Wannon is a "captured 

 consequent," while the central part may be called an "insequent " 

 stream (a term used by Andrews, " Physical C^^eography of N.S.W.," 

 p. 36). 



The deeper valley of the Lower Wannon is now endeavouring 

 l:>y means of headward erosion, as at the Wannon and Xigretta 

 falls, to reduce the three parts of the stream to a more harmonious 

 grade. The events are so recent, and the evidence so clear, that 

 any geological map of Victoria will evidence the truth of this 

 theory; especially is this so if taken in conjunction Avith the more 

 ■detailed county maps as to the nature and direction of the river's 

 course. 



It should be noted also that of the two older tracts of the Wannon, 

 the lower one — from Tahara to Casterton — is Avholly due to erosion. 

 The upper part, Avithin the Grampians, lies in valleys that are 

 probably of tectonic origin, and older than the Tahara-Casterton 

 portion. 



(c) Wando and Wando Vale Ponds. — These tAvo streams rise in 

 the Avestern part of the Dundas highlands, and Aoav south-Avesterly, 



