RELATION OF STREAMS TO GEOLOGICAL STRUCTURE. 57 



Fig. 2. 



The same principle holds good if a consequent stream, 

 working backwards, finds a barrier of resistant rock across 

 its path. Instead of heading back through the barrier, it 

 begins to throw out feelers, as it were, along the margin. 

 This is well illustrated, as Andrews has pointed out, 1 

 by the Clarence River in New South Wales, where the 

 courses of the north and south arms have been determined 

 by an elongated mass of resistant New England granite 

 running almost parallel to the coast and not quite at right 

 angles to the course of the river. The result has been the 

 production of a boathook bend where the south arm joins 

 the main stream, while the junction of the north arm is a 

 normal one. 



Yet one more suggestion of a reason for the existence of 

 boathook bends may be advanced, which is possibly applic- 

 able to some of the rivers of New South Wales. It may be 

 that a stream is flowing towards the sea, when slow coastal 

 uplift takes place, with a tilt inland. If the river has 



1 New South Wales Handbook, B.A.A.S , 1914 p. 512. 



