SURFACE. 21 



Eain which falls within 400 yards of the Arkansas 

 runs into Pawnee Fork, keeping nearly parallel to the 

 larger stream for 200 miles, before finally uniting with 

 it. These rains falling on and running over the newly 

 upheaved and soft materials of the plains, have rounded 

 the higher portions into long and gentle slopes, each, 

 however, terminating in a ravine, which becomes deeper, 

 wilder, and more tortuous until it has entirely cut its 

 w r ay through the second plain. When the ground is high 

 and the 'divides' between the streams narrow, these 

 streams are exceedingly precipitous and difficult, and to 

 travel through them with waggons is a work of art. 



The streams which take their rise in the mountains 

 cut their way through the second plain in canons more 

 or less wide and deep, depending on the nature of the 

 material encountered. The South Platte (at first deflected 

 from its natural course, and sent to the northward by 

 the immense mass of debris washed from the mountains 

 and deposited in the sea as a bar) gets through with dif- 

 ficulty, but cutting no very remarkable canon, the 

 materials through which it made its way being of such 

 a nature as to be rapidly rounded into hills and easily worn 

 away into slopes. 



The Arkansas cuts through the same ' bar,' but en- 

 counters from the second plain a more rigid resistance 

 than the Platte, and it gets a long way from the moun- 

 tains before fairly out of canon. 



The tributaries of the Arkansas, which take their rise 

 in the mountains, cut splendid canons for their passage. 

 Of these the finest is that of the ' Purgatory,' which for 

 more than fifty miles is almost shut out from the light 

 of day by beetling cliffs of red sandstone, 800 to 1,000 

 feet high, and in many places within a very few hundred 

 feet of each other. 



The Cimarron, rising on the west side of the great first 

 plain or Eaton Mountains, runs at first to the southward ; 

 then, turning abruptly to the east, cuts its way through 



