DILUNAGE CHANGES OF THE SHENANDOAH 363 



Drainage changes during the recent cycle have been insignificant and 

 of comparatively little importance. Such as have occurred seem to be 

 chiefl}' of the intercision type* of pirac3', where incised meanders of two 

 neighboring streams working on the opposite sides of a divide finally cut 

 through and the larger stream, since it is flondng at a lower level, captures 

 the waters of its neighbor. An interesting case of this kind has occurred 

 in comparatively recent times at Bridgewater. Dry River formerly en- 

 tered North River about one mile southeast of the town. One mile 

 northwest of the town the valleys of the two streams are separated for 

 a short distance by a prominent chert ridge. Both streams were flowing 

 in meandering courses and each chrected its current against opposite points 

 in the ridge. Finally the ridge was cut through and North River, being 

 the larger stream and flo\sang at a lower level took the waters of Dry 

 River. So recent has been this capture that the two streams do not meet 

 at grade and there is a small fall in Dry River a few yards above their 

 junction. Another instance of this t^npe of capture about to occur is 

 near Mt. Cra^^ord where North River is about to intercept another of 

 its tributaries in the same manner about one mile above their present 

 junction. 



*An earlj' paper by the writers will be devoted to a description of the inter- 

 cision type of piracy in the Shenandoah Valley Region of Virginia, several cases 

 of which are known and have recently been studied. 



