,'516 PUOCEEDIXCS OF SECTIOX C. 



10.— NOTES OX T?[E rHYSlOGRAPHY OF NORTH QUEENSLAND. 

 Bij W.V. POOLE, B.E.. F.G.s. 



Two and a-lialf years ago, wliile travelling to Mount Molloy 

 fi-oru Biboolua, the writer noticed the long stretch of flat plain extend- 

 ing from the Barron Kiver, at Biboohra, in the direction of Mount 

 MoUoy. On the return journey, via the Two-mile Creek, the writer 

 saw a low, w'ide, billabong-like creek, coming Avitliin 1^ miles of the 

 Barron IJiver. On iiLquiry the writer was astonished to find that the 

 creek ran into the Mitchell and not to the Barron. Time did not 

 then peiDiit of further investigation, but the opinion was then advanced, 

 that this was an instance on a large scale of river capture, in short, 

 that the BaiTon above this localitv was formerlv the head waters of 

 tlu' Mitchell. 



After heavy rains the surface water at ])oints as near as jto ^ 

 mile fi'om the banks of the Bai'inn flows away in the opposite direc- 

 tion to the Mitchell. The grade in this direction is so flat that the 

 plains are under water for some time after heavy tropical rains. 

 Tliere are large swam})s in the intervening strip of two miles between 

 the Barron Hivei' and Two-mile Creek. These two streams flow across 

 a flood plain of recent fluviatile alluvium. The hydraulic grades of the 

 Two-mile Creek and Mitchell are flat, while that of the Barron is 

 much steeper; tlie latter stream, even when low, flows with a fairly 

 rapid current. The Barron has not been known, during the ])eriod of 

 white settlement, to overflow its banks on to the plains at this locality. 

 The bed of the stream at Biboohi-a is still in the stage of incipient re- 

 juvenescence. The writer is of o])inion tliat the capture of the upper 

 waters of the Mitchell at this ]ioint is of veiy recent date. It is 

 ju'obable that to the east the neighbouring streams of meridional 

 dii-ection have been successively captured at earlier dates. The wi'iter 

 had not time, however, to pursue investigations in this diiection. 



The U}iper Barron, which has been capturefl. from the Mitchell, 

 is tlie main contributing stream of the Barron River. The capture of 

 this stream and the probable ca])ture of other contributing streams 

 f]'om the Mitchell will have undoubtedly increased the erosive action 

 at the Barron Falls. These falls, the largest in Australia, are about 

 1,000 ft. high, and are situated at the end of a deep gorge about 3 

 nules long. The retrocession of the Barron Falls and the elongation. 

 of the gorge have left as hanging valleys the beds of tributary 

 streams, such as Surprise Creek. This creek joins the lowei- Barron 

 iji falls of about 1,000 ft. down the steep face of the gorge. It is 

 interesting to note that the Barron Falls have cut back 1.^- miles from 

 tliis point, while the Surprise Creek Falls have cut back only about 

 70 yds. f]-om the face of the gorge. 



The ])hysiograpliy of this portion of the country presents some 

 interesting features. Tlie high land in which the Bari'on rises may 

 be termed the Mother of K'ivers from the number of large and 

 important streams lising therein — viz.. Barron, Mulgi'ave, Russell, 

 Johnson. Wild and Walsh Rivei's, the last-mentioned flowing to the 

 Gulf of Cai'pentaria. All of these streams head Avitliin a few miles of 

 each othei-. The mnuntaitis range up to -'5,700 ft. in lieiglit. There 

 are numerous extinct volcanoes studded thi'oughout this distiict, many 

 of them existing as dry craters or crater lakes; tlie rainfall is abmi- 

 dant. and the soil very fci-tilc. Bcllcndoii-Kei-, in tlie iMulLjrave.-Russell 



