340 BUFFALO LAND. 



they been roasted and crystallized by internal heat. 

 Although limestone rock, they easily yield to the ac- 

 tion of water, and so the side drainage into the 

 creeks and rivers has removed their high banks to 

 from many rods to many miles from their original 

 positions. In many cases these banks or bluffs have 

 retained their original steepness, and have increased 

 in elevation as the breaking-down of the rock en- 

 croached on higher land. In other cases the rain- 

 channels have cut in without removing the interven- 

 ing rocks at once, and formed deep gorges or canyons, 

 which sometimes extend to great distances. They 

 frequently communicate in every direction, forming 

 curious labyrinths, and when the intervening masses 

 are cut away at various levels, or left standing like 

 monuments, we have the characteristic peculiarities 

 of " bad lands " or mauvaises terres. 



In portions of Kansas tracts of this kind are 

 scattered over the country along the margins of the 

 river and creek valleys and ravines. The upper 

 stratum of the rock is a yellow chalk; the lower, 

 bluish, and the brilliancy of the color increases the 

 picturesque effect. From elevated points the plains 

 appear to be dotted with ruined villages and towns, 

 whose avenues are lined with painted walls of forti- 

 fications, churches, and towers, while side alleys pass 

 beneath natural bridges or expand into small pockets 

 and caverns, smoothed by the action of the wind, 

 carrying hard mineral particles. 



But this is the least interesting of the peculiarities 

 presented by these rocks. On the level surfaces, de- 

 nuded of soil, lie huge oyster-shells, some opened and 



