THE WORK OF RUNNING WATER. 



149 



belts along the flanks of the truncated folds {ab and cd, Fig. 133). The 

 streams, esx)ecially the lesser ones, now flow along the strike of the 



Fig. 135. — Diagram to illustrate readjustment of drainage, as base-level is approached. 



Fig. 136. — Diagram to illustrate superimposition. The consequent stream on the 

 upper formation is superimposed on the underlying structures when the upper 

 bed has been cut through. 



softer beds much more commonly than elsewhere, and where they 

 cross the hard layers it is usually at right angles to the strike. This 

 is shown in Fig. 134, where the arrows indicate the direction of strike. 



