THE WORK OF RUNNING WATER. 



187 



are usually aggrading streams. In general, anything which greatly in- 

 creases the load of a stream near its head is likely to cause deposi- 

 tion, and so the development of a flood plain, at some point farther 

 down the valley. 



Fig. 176. — Anastomosing of a depositing stream. Yahtse River, Alaska. (Russell, 



U. S. Geol. Surv.) 



Streams which are actively aggrading their valleys are likely to 

 anastomose (Figs. 176, 177). This results from the filling of the channels 



Scale. 



Fig. 177. — Anastomosing of the Platte Rive, Dawson Co., Neb. (U. S. Geo!. Surv.) 

 until they are too small to accommodate all the water. The latter then 

 breaks out of the channel at few or many points. The new channels 

 thus established suffer the same fate. 



