T. 8. Ellis — Biver Curves. 35S 



right augles to another, the two would produce a resultaut of 

 direction. Still, I believe that only in exceptional cases would 

 a river be thus diverted towards the opposite side. The rock 

 material which such an affluent would probably bring down and 

 throw into the river on either side of its own course (forming 

 a ' cone ') is much more likely than is the impact of stream- against 

 stream to be the real diverting influence. 



Dr. Callaway, while recognizing the fact which I had pointed 

 out, that rivers do, as a rule, bend towards their affluents, gives an 

 explanation differing from mine. He argues that the resultant of 

 the two streams will have the effect of carrying the principal part 

 of the detritus brought down by the affluent across the course of the 

 river obliquely down-stream, depositing the suspended matter near 

 the bank on the opposite side. He regards the shoal-bank thus 

 formed as the initial cause of the river curve. I cannot accept this. 

 Large rivers curve which have at the convexity a very small affluent 

 only, just enough to cut the bank down to the river-bed. It is 

 difficult to imagine that the small amount of suspended matter 

 which could have come down such a stream would have had 

 any effect separate from that due to the very much larger amount 

 brought down by the river itself. Moreover, it is at flood-tim© 

 that most of the suspended matter is brought down. Then the 

 river channel is effaced, a sheet of water covering it and the 

 adjoining land as well as the mouth of the affluent itself. What 

 influence could there be that would determine the dropping of the 

 principal part of the suspended matter brought down by the affluent 

 just within the line of the bank on the opposite side of the river? 

 I can readily imagine that, in the swirling confusion caused by the 

 (literal) con-fusion of the two streams, suspended matter would be 

 likely to fall beneath the current and sink to the bottom at once, 

 and I have seen an affluent after a flood cutting a new passage at 

 its mouth through mud within its own banks. Nor, when the river 

 is not overflowing, can I imagine an affluent that had just enough 

 momentum to carry suspended matter across the stream, but not 

 enough to injure the banks on the opposite side. 



In my view, the important question is, not where is sediment 

 deposited — it is deposited everywhere — but in what part of the river- 

 bed is it allowed to remain ? As I say, it remains where a channel 

 is not necessary. 



Professor Davis, also writing in this Magazine (April, 1903)^ 

 states that " rivers cannot be habitually straight in their initial 

 stage." Why not ? An inquiry into the cause of river curves 

 implies the supposition that, in the absence of a diverting cause, 

 there will be no curve. This is my belief. But if " the bends with 

 which rivers begin are as a rule spontaneously exaggerated in 

 their later development," why not all of them ? He adds that " in 

 advanced maturity the river must always be curved." Father 

 Thames is fairly mature, but he has long straight reaches. Theories 

 are generally regarded as good according as they are sufficient 

 to explain phenomena which are manifest. Can the erratic course 



DECADE IV. — VOL. X. — NO. VIII. 23 



