88 



PHYSIOGRAPHY 



standing water, as it may, it becomes the site of a lake (Fig. 91, and 



Fig. 1, PL XVII, p. 64). Such lakes are called oxbow lakes, or bayous. 



In meandering, a stream sometimes reaches and undermines 



the valley bluff, thus widening its valley flat (PI. VIII, p. 13). This 



Fig. 89. Fig. 90. 



Fig. 89. Diagram illustrating an early stage in the development of river 



meanders. The dotted area represents the area over which the stream 



has worked. 

 Fig. 90. A later stage in the development of meanders. 



is, indeed, the most important process in the widening of valley 

 flats. While river deposition sometimes makes river flats (Fig. 86), 



Fig. 91. A series of diagrams showing various stages in the development of 

 meanders. (Robin.) 



and while it always tends to widen them because it builds up their 

 surfaces, it should be remembered that erosion at the sides of the 

 channel is the most important process in their development. 



