552 A STRIKING EXAMPLE OF RIVER-CAPTURE, 



not been so recent but that the valley has been gouged out to a 

 depth of 1600 feet since it took place (fig.3). 



GEOLOGICAL SECTION ALONG LINE ftBC 



Fig.3. — Geological section along the line A, B, C on the map (Plate xlii. ). 

 The representation is slightly diagrammatic. The curves for Silurian slates 

 indicate only that these rocks are intensely contorted and do not represent 

 the actual folds. The Silurian marble is conformable with the slates; its 

 extent in the direction of the line of section is small. Thicknesses of Permo- 

 Carboniferous and Triassic rocks and of basalt are diagrammatic. 



A similar process of piracy of Wollondilly water by the 

 Shoalhaven system is imminent a little further north. In the 

 neighbourhood of Bundanoon the Bundanoon Greek occupies a 

 gorge very similar in depth to that of the Shoalhaven at Tallong. 

 Into the head of this valley the creek plunges over a magnificent 

 series of waterfalls. The railway runs along the razor-backed 

 divide between Bundanoon Creek on the east and Paddy's River 

 (a tributary of the Wollondilly) on the west. Paddy's River 

 flows along through a very broad U-shaped valley at an elevation 

 not much under 2000 feet above sea-level. In places the head of 

 Paddy's River is not more than ten chains from some of 

 the headwaters of Bundanoon Creek. With this structure, the 



