18-1: GEOLOGY OF QUEENSLAND COAST, 



fined between vertical limits of 5 and 20 feet, traces of contem- 

 poraneous elevation exist inland from Townsville to the extent 

 of 300 feet; terraces also occur at Raymond Terrace about 20 

 feet above sea level, while some 10 miles to the west traces of 

 the upward movement occur as much as 50 feet above present 

 high water mark. From observations made in North Queensland 

 and along the New England plateau the topographical features 

 of the central and eastern portions of the cordillera record a 

 double cycle of elevation. The hydrographic system was dis- 

 turbed ; the broad shallow basins which had been developed 

 in the plateau after the Tertiary basalt outbursts were forced 

 upwards again in much more recent times, the criteria of later 

 elevation consisting in the ''valley in valle}- " form of the river 

 systems. The canons of such rivers as the Macleay, 2,000 to 

 4,000 feet deep, occupy the centres of their former basins, and 

 end in gigantic waterfalls sometimes 1,000 feet in height. Other 

 e.xamples of recently disturbed drainage systems are : — 



(1) The Barron, Tull}^, and Johnson falls in N. Queensland. 



(2) The various Clarence and Macleay falls in New England. 



(3) The Nepean and Shoalhaven falls in southern N.S. Wales. 

 A youthful stage in stream development is also hinted at by 



the "strike" streams of the upper waters of the coastal rivers. 

 More steeply graded rivers travelling westwards from the coast 

 may hereafter catch the long meridionally disposed headwaters of 

 streams like the Clarence, Shoalhaven and Nepean. 



The recent epicycle of elevatory coastal movement accentuates 

 such features as island tying, the formation of lagoons, coastal 

 plains, bay bars and silting up of bar-bound harbours. 



Such rivers as the Brisbane, Richmond, Clarence and Macleay 

 furnish magnificent examples of the dominance of a southern 

 along-shore current, and the evident intention of the sea to 

 establish a straight shore line in the enormous deflection north- 

 wards of these streams and the presence of liuge bars at their 

 mouths. Other evidence of the influence of sea action is manifest 

 from the position of Frazer Island, the uninterrupted sweep of 

 its eastern coast, its extensive northerly spit, and the gently 



