414 FIRST YEAR SCIENCE 



huts or hogans, are but scattered remnants of what was 

 formerly widespread. 



On old plateaus travel is easy. There are no deep 

 valleys, and one can easily pass around the mesas, which only 

 add charm to what would otherwise be a most monotonous 

 landscape. When these mesas are high, they are some- 

 times occupied by a few Indian tribes who have fled to 



CLIFF DWELLINGS. 

 A protected retreat in a mesa. 



them for protection, as the medieval barons when hard 

 pressed fled to their isolated castles. 



193. Broken Plateaus. The force which has uplifted the 

 plateaus is not always uniform enough in its action to lift 

 large areas without fracturing the rock layers. Thus 

 plateaus are found which have the rock layers broken and 

 displaced. The layers on one side of the break may stand 

 thousands of feet higher than those on the other side. 



This is seen in the region of the Grand Canon of the 

 Colorado, where the Kaibab Plateau stands about 2000 



