58 /. A. Leach: 



gorge back across other streams. The original streams are 

 beheaded, and their waters diverted into the subsequent streams. 



There has been a considerable boom in surface tension. It 

 has been called in to explain, or at least to be held in some way 

 responsible for, many divergent phenomena. The geologist, so 

 far, has not claimed much from it, but here we can see it is 

 proving a remarkably efficient aid in the rapid denudation of 

 parts of the earth's surface. 



In many parts of Victoria, even away from the coast, where 

 there has been possibly a recent uplift to rejuvenate the streams, 

 canyons are being formed. On the gold-fields the softer alluvial 

 drifts also are being rapidly worn into canyons and bad lands. 



In conclusion, we have seen that in at least three ways surface 

 tension is an important aid in denudation by enabling water to 

 adhere to an undercut face. 



1. Even where there is a waterfall, with its consequent splash, 

 some water at least trickles down, adhering to the face through- 

 out. By this means soft beds are trickled out. The harder 

 bands, being unsupported, then break off. 



2. Where there is not a permanent stream, sui'face tension is 

 a most important agent (especially if there is only a small 

 quantity of water), in assisting in the wearing-back of the head 

 of a gorge. It is also of great importance in widening out a 

 canyon and in the formation of tributary gorges and bad lands. 



3. It is an important agent in river-capture by enabling a small 

 quantity of water to attack the softer underlying layers, and so 

 remove them. Thus it cuts back and across other streams. 



It is to be distinctly understood that the general question of 

 denudation and denuding agents is not discussed here. The 

 point is the importance of the surface film as an agent in under- 

 cutting, as opposed to the splash from a waterfall. Thus the 

 surface film becomes an aid in corrosion and erosion. 



