220 



EARTH FEATURES AND THEIR MEANING 



uplift has produced the modern river valleys which are cut out of 

 the plain. The plexus of long threads of the coarser materials are 

 the courses of dwindling rivers which interlaced over the former 



FIG. 235. Section across the great lenticular threads of alluvial deposits which 

 compose the veneer of the High Plains (after W. D. Johnson). 



plain, and which in time were buried under other channel deposits 

 of the same nature but in different positions (Fig. 236). The 



pluvial periods in which this 

 bench was formed produced 

 in other latitudes the great 

 continental glaciers which 

 wrought such marvelous 

 changes in northern North 

 America and in northern 

 Europe. * 



Character profiles. In 

 contrast with the profiles in the landscapes of humid regions (see 

 Fig. 187, p. 177), those of arid lands are marked by straighter 



FIG. 236. Distributaries of the foothills 

 superimposed upon an earlier series (after 

 W. D. Johnson). 



Bench 



FIG. 237. Character profiles in the landscapes of arid lands. 



