OLD PLATEAUS 



413 



are found in the Allegheny and Cumberland plateaus, ex- 

 tending from New York to Alabama. 



192. Old Plateaus. If a plateau remains elevated for a 

 great length of time, the dissecting rivers are able to widen 

 their valleys and wear away all the interstream spaces, 

 except where these are very broad. Thus the rivers bring 



AN INDIAN HOGAN. 



the surface down to a comparatively low level, with here 

 and there a remnant which has not been worn away, but 

 which shows in its steep sides the edges of the rock layers 

 which formerly spread over the whole region. If these 

 residual masses are large, they are called by the Spanish 

 name mesas, meaning tables, and if small, buttes, from the 

 French word which means landmarks. 



Some of these mesas are so high and so steep that it is 

 impossible to climb them, and others are simply low, flat- 

 topped hills. A traveler in New Mexico and Arizona 

 will see many of these mesas, which, like the lonely Indian 



