KIVERS OP NEW SOUTH WALES. 393 



but lies through immense phxins whicli fall away from the river 

 towards the south as well as towards tlie west. Hence, when a 

 flood takes place and the ordinary channel proves insufficient to 

 carry it off, overflows occur in a southerly and south-westerly 

 dii'ection. These overflows are numerous, and some of them come 

 into operation at a comparatively low level of the river ; while 

 others have never been known to act except in 1870. Of the 

 efiiuents which carry a portion of the flood waters of the Mur- 

 rlimbidgee to the Billabong Creek, the most valuable is the 

 Yanko Creek, which is a most important natural distributary by 

 itself, and llie value of which is greatly enhanced by the sub- 

 divisioii of its waters at the Colombo Creek head. Although, 

 under present conditions. Lake Urana receives a share of the 

 waters of the Murrumbidgee only in exceptionally high floods, 

 and even then only by overflow from the Colombo Creek, it is by 

 far the most important of the lakes whicli that river can supply. 

 The other lakes wliich depend wholly or chiefly on the flood waters 

 of the Murrumbidgee are all situated below the junction of that 

 river with the Lachlan. The most important of these are Lakes 

 Tala and Yanga on the east side of the river, and Lakes Paika, 

 Macommon, Ptarpunga, Tori, Merimlee, and Waldaira on the west 

 side. 



In the case of the Macquarie River, not only does the channel 

 entirely disappear at the Macquarie Marshes, but it may safely be 

 inferred that the process of silting up is in progress from the 

 Marshes up to near Narromine. In proof of this, I found that the 

 sectional area of tlie river at Dubbo is much greater than at 

 Warren, and that the diminishing channel between these places 

 is altogether unequal to the task of discharging the flood water. 

 As the Murrumbidgee ceases to flow in a valley near Narrandera, 

 so the Macquarie ceases to flow in a valley after it passes the 

 neighbourliood of Narromine. Hence we And that during floods 

 there is a series of overflows from near Narromine down to the 

 place where the channel disappears, a considerable portion of the 

 water reaching the Began River through the Beleringar, Gun- 

 ningbar, and Duck Creeks. 



The Lachlan aflbrds another instance of what may be termed 

 the old age of a river. Its case is almost an exact parallel to that 

 of the Macquarie; the channel being a gradually diminishing one, 

 while the surplus flood waters which are not carried ofl" by eflluent 

 creeks are lost in the reed beds at the junction with the Murrum- 

 bidgee ; only a small portion of tlie higliest floods reacliing the 

 latter river. Lake Carjelligo, or Cudgellico, as it is frequently 

 ■called, occupies the same position in regard to the Lachlan, as the 

 lakes on the lower part of the Murrumbidgee do to that river ; 

 that is, it receives a supply of water when the river is in flood 

 and allows a large portion of it to escape as the river falls. The 

 most important eflluent from the Lachlan is the Willandra 



