The Rivers and Yalleys of Pennsylvania. 



211 



The consequences resulting from readjustments of this kind by 

 which their recent occurrence can be detected are : a relatively 

 sudden increase of volume of the divertor and hence a rapid 

 deepening of the course of the diverting stream, FE, and of the 

 diverted, AF, near the point of capture ; small side-streams of 

 these two being unable to keep pace with this change will join 

 their masters in local rapids, which work up stream gradually 

 and fade away (Lowl, Penck, McGee). The expanded portion, 

 ED, of the larger stream, CD, already of faint slope, may be 

 locally, overcome for a time with the increase of detritus that will 

 be thus delivered to it at the entrance, E, of the divertor ; while 

 the beheaded stream, HB, will find itself embarrassed to live up 

 to the habits of its large valley [Heim]. Geographic exploration 



Fig. 16. Fig. 17. Fig. 18. 



with these matters in mind offers opportunity for the most 

 attractive discoveries. 



18. Examples of adjustment. —Another case is roughly figured 



