THE WORK OP STREAMS 



155 



Intrenched meanders, interrupted profiles of streams, 

 even-crested mountain ridges, and certain kinds of terraces 

 are accordingly among the features which may indicate 

 more than one cycle of erosion, and which often aid in work- 

 ing out the later geological history of a region. 



Questions 



1. At what stage in an erosion cycle is the run-off greatest ? 



2. At what stage in their development are rivers most subject 

 to destructive floods ? 



3. When in an erosion cycle is the general level of the ground- 

 water surface highest ? Lowest ? 



4. What is (1) the immediate, and (2) the final, effect of stream 

 erosion upon topography ? 



5. At what stage of an erosion cycle is agriculture most favored ? 



FIG. 148. View in the western part of the province of Chi-li, China. The 

 erosion of the gneissic rocks has been aided by recent deforestation. 

 (Willis, Carnegie Institution.) 



