58 W. ». BROWNE. 



sufficient erosive energy it may succeed in keeping its 

 course against the uplift, in other words it may become an 

 antecedent stream. Now in the new cycle of erosion 

 initiated by the uplift a certain amount of drainage will 

 take place in an inland direction, and under these circum- 

 stances we might expect to find a main river flowing 

 seawards against the rising ground, while those of its 

 tributaries developed as a consequence of the uplift are 

 flowing inland and forming boathook bends (Fig. 3, a and b). 



A similar ultimate result might be brought about if* the 

 uplift was uniform, and raised a terrane consisting of level- 

 bedded soft sediments overlying harder strata with a gentle 

 inland dip. Immediately subsequent to the uplift the con- 

 sequent tributaries would probably be normal in character, 

 but eventually, when the softer strata were removed by 

 denudation and the harder, underlying dipping strata 

 formed the land surface, there would naturally result 

 inland-flowing tributaries. 



An interesting physiographical problem is presented by 

 the relation of the Shoalhaven River to its tributary* the 

 Kangaroo. The tributary meets the main stream betweeu 

 the right-angled bend at Tallong and the sea, and it makes a 

 pronounced boathook junction. Taylor again sees in this 

 fact evidence for a former western course for the Shoal- 

 haven, but an examination of Harper's beautiful stereogram 

 of the South Coast District shows that the gradual slope 

 upwards in the land surface from the Sydney depression 

 comes to an end about Robertson, from which point the 

 tilt of the land surface (virtually the dip of the Hawkes- 

 bury Sandstone) which has been to the north and west, 

 now changes to a slight but noticeable tilt to the south 

 and west. It is through this country that the lower 

 Shoalhaven flows, and it is here that the Kangaroo takes 

 its rise — and, quite appropriately, a few leaps. 



