THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE IV. VOL. X. 



No. IV.— APRIL, 1903. 



I. — The Development of Rivee Meanders. 



By Professor "W". M. Davis, Harvard University, Cambridge, Mass. 



THE paper by Dr. Callaway, "On a Cause of Eiver Curves," 

 in the Geological Magazine for October, 1902, suggests 

 comment for two reasons : first, because the cause that he brings 

 forward seems of doubtful application ; second, because the habitual 

 entrance of branch streams at a certain part of the curves of 

 main streams is satisfactorily explained by controls which seem to 

 be of surer and more powerful application than the control which he 

 advocates. 



In ascribing to a tributary the power to make a main stream bend 

 in a definite manner towards the tributary, and thus determine the 

 habitual entrance of tributaries on the convex side of the main 

 stream's curves. Dr. Callaway argues that the detritus brought by 

 the tributary will be deposited on the further side of the main 

 stream and somewhat below the tributary's mouth. Various 

 examples known to me of the deposits formed by side streams in the 

 channels of main streams do not bear out this conclusion : the 

 detritus is not deposited on the further side of the main stream, but 

 as a delta at the mouth of the tributary or a little below it ; and the 

 main stream does not bend toward, but away from the tributary. 

 The Rhine, the Colorado, and many other rivers that might be 

 instanced, show abundant examples of this kind. Moreover, the 

 assumption of an initially straight main river, as stated by 

 Dr. Callaway, involves an extreme improbability. Rivers cannot be 

 habitually straight in their initial stage, and the bends with which 

 they begin are as a rule spontaneously exaggerated in their later 

 development. The processes by which the initial bends are 

 developed into meanders, and by which the meanders are persistently 

 maintained when once developed — entirely independently of the 

 action of tributaries, — are too important to be omitted from the 

 problem in hand: above all, they should not be replaced by 

 a doubtful or at most a weak process. 



DECADE IV. VOL. X. NO, IV. 10 



