500 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



begin this action just at the beginning of the curves), and on the down- 

 valley side of short tangents. The curves will thus increase in radius 

 and arc and the meander belt will widen, while each meander will tend 

 to move slowly down the valley. The flood plain must be scoured out 

 for a certain stretch, N N 1 , around the concave banks and along the up- 

 valley side of every lobe; while a scroll of new flood plain, M M, is 

 added around the end and on the down-valley side of the lobe. 



Fig. 7. 



All this may be easily recognized in the meanders of a meadow brook ; 

 and that it occurs even in the Mississippi is abundantly illustrated in 

 the large-scale maps (three inches to a mile) published by the Missis- 

 sippi River Commission (see specially Charts 36, 38, 39), where the 

 lines of flood-plain growth pass around the end and along the down- 

 valley side of each lobe, while they are cut across by the encroaching 

 river on the up-valley side of the lobe, as indicated in Figure 7. Still 



