374 The National Geographic Magazine 



The Theiss, Basin of Hungary 



in every conceivable direction with re- 

 spect to their own axes and the trend of 

 the river. Certainty there is great diver- 

 sity, even appearance of disorder, here. 



But when the processes that are 

 changing geographic forms are studied, 

 system and law become at once more 

 evident ; not that the process is more 

 systematic or observant of law than the 

 resultant forms, but only a mind con- 

 scious of process can perceive the sys- 

 tematic element in the forms. At even- 

 bend is the stream-cut bluff without and 

 growing sand bar within. Along each 

 wavering stretch lie the oxbow lakes 

 and sloughs to right and left. Every- 

 where are seen signs that the river, 

 wandering too far to right and left in 

 its meandering stretches, recovers itself 

 by cutting off loops it has planned be- 

 yond its powers, to again stagger aim- 

 lessly, gathering momentum across its 

 valley as its thread rebounds from bank 

 to bank and presently begins meander- 

 ing anew. 



To measure the width of the belt of 

 meanders between lines tangent along 

 the swings of the river to right and left 

 is to measure a varying quantity that 



finds its minimum in wavering reaches 

 and its maximum in some strong group 

 of meanders. This value must be se- 

 lected as characteristic of the river, since 

 the river's swinging tendency finds in 

 it its fullest expression. 



There are many difficulties in the 

 measurement of meander belts. In 

 practice, judgment is aided by the pres- 

 ence of cut-off loops and by the empir- 

 ically determined fact that streams rarely 

 attain their maximum width of meander 

 until the belt is two or three times as 

 wide as the successive loops are distant 

 along the general course of the river. 

 This ratio is given for the rivers for 

 which data are tabulated at pages 378 



and 379 under the heading — , or mean- 

 der belt divided by distance. It gives 

 an excellent idea of the stage of devel- 

 opment of any system of meanders. 



WHY VOLUME IS NEGLECTED 



We have very little accurate knowl- 

 edge of stream discharge to obtain good 

 data for the rivers that are otherwise 

 suitable for meander study. 



