16 PHYSICAL GEOGRAPHY. 



lican. The character and origin of these sand hills will be dis- 

 cussed in the chapter on the superficial geology of the State. Suffice 

 it here to say that these sand hills are being covered by the increas- 

 ing rainfall of the State with nutritious grasses, and are becoming 

 fine grazing grounds. While principally composed of sand they 

 also contain a large amount of potash, soda and lime, and these 

 fertilizers start vegetation as soon as there is a sufficiency of 

 moisture. 



Bad Lands. 



The bad lands run into northwestern Nebraska, but cover a very 

 limited area mainly beyond the White River. They are made up 

 of indurated sands, clays and marl, and occasional layers of thin 

 hard rock. They have been cut up into deep canyons and ravines 

 by atmospheric agencies. The sides, until the talus at the bottom 

 is reached, are often vertical and sometimes capped at the top with 

 a hard rock that projects beyond the sides. Often without a parti- 

 cle of vegetation the isolated cones, columns and peaks look in the 

 distance like towers, pyramids, cathedrals and obelisks, resembling 

 the ruins of the eld cities of the Orient. The geological age and 

 the character of the fossil plants and animals will be discussed in 

 the chapter on the Tertiary Age. 



