F}tysiograp}iy of the Glenelg River. 109 



As the land rose the Glenelg would continue to deepen its valley 

 and increase its territory. In the soft Jurassic rocks the valley is 

 wide, and flood-plains, cut-offs, and terraces are to be seen ; but in 

 the somewhat harder, level-bedded limestones lower down the 

 course, below Dartmoor, the river has cut down into a steep valley 

 with high precipitous cliffs that still persist. 



At this time we may picture two chief tributaries of the Glenelg 

 — an eastern one, the Wannon (W. Fig. 2), and a more northern, 

 to which we may give Mitchell's name — the Nangeela valley (N. Fig. 

 2). The Nangeela would have everything in its favour to proceed 

 with vigorous headward erosion, and we may picture it advancing 

 more and more to the north, rounding the Dundas highlands, and 

 ultimately, one by one, capturing the struggling northward 

 streams, eventually reaching back into the territory of the Wim- 

 mera itself, as indicated in Fig. 2. 



In August, 1836, Mitchell'^ made the following observations re- 

 garding the flow of the river at a point about four miles north of 

 the junction w4th the Stokes River : — Average breadth, 35 yds. ; 

 mean depth, 17 ft. ; velocity of current, 1863 yds per hour. This 

 represents a flow of about 62,000,000 gallons per hour. The river 

 is subject to very severe floods, when, of course, the flow is even 

 greater. On the other hand, in summer time, the surface flow often 

 practically ceases. This was the case at the time of our camp 

 there in January, 1914. 



The absence of any deep, Avide estuary at the mouth of the Glenelg 

 was a great disappointment to Mitchell. The mouth is shallow, and 

 shoaled with shifting sand bars. On August 20, 1836, Mitchell 

 wrote in his journal : " The day was squally, with rain, neverthe- 

 less, during an interval of sunshine I obtained the sun's meridian 

 altitude, making the latitude 38° 2' 58" S. I also completed, by 

 2 p.m., my survey of the mouth of the river and the surrounding 

 country. ... On re-entering the river from the sea, I presented 

 the men with a bottle of whisky, \vith which it was formally named 

 the Glenelg, after the present Secretary of State for the Colonies." 



(b) The Wannon.; — This tributary, whose native name has for- 

 tunately been preserved by Mitchell, was favourably placed in the 

 soft Jurassic and tertiary rocks. There are, however, two or three 

 features in the present Wannon valley that demand explanation. 

 The valley may be divided into three very distinct tracts. In the 

 lower Wannon, from Tahara to Casterton, we have a fine stream, 



1 Journal, vol. ii., p. 218. 



