SURFACE. 35 



during the summer and fall the dry season are from 

 the south-west ; yet, however much the form and 

 position of the sand-hills on the south side of the river 

 may change, there is scarcely a particle of sand to 

 be found on the north bank, nor a single sand-dune 

 formed outside of what can readily be distinguished as 

 the old limits or boundaries . of the sand-stream. Just 

 opposite Fort Dodge this stream narrows in one place to a 

 few yards. The waggon road to Camp Supply crosses at 

 this narrow place, and saves many miles of weary labour. 

 Twenty-five miles below Fort Dodge the Arkansas bends 

 to the north-east ; the sand-stream attempts to follow, but, 

 apparently unable to turn so sharply, compromises the 

 matter by keeping near the river with the northern edge, 

 while the south edge stretches in nearly a straight line to 

 the east in continuation of its former course. The con- 

 sequence is, that the sand-stream becomes nearly forty 

 miles wide, and so extremely difficult to cross with 

 loaded waggons, that buffalo-hunters, and other people of 

 that section, prefer to turn it by the longer road, vid 

 Fort Dodge. 



Another of these sand-streams follows the general 

 course of the Cimarron. Another, and an especially bad 

 one, passes eastward between Wolf Creek and the Cana- 

 dian. Numberless others could be mentioned if necessary, 

 Their general characteristics are the same as of the ex- 

 ample given. 



I must mention one, more remarkable than any other 

 of which I have knowledge, which, though lying in the 

 limits of the second plain, is not within the limits of the 

 United States. Starting in the south-west of the territory 

 of New Mexico, and running in a south-easterly direction 

 through the Mexican State of Chihuahua, nearly parallel 

 to and from fifty to seventy miles from the Eio Grande, 

 this sand-stream has a length of over 100 miles 

 by a breadth of twelve or fourteen. This stream is a 

 succession of bare rounded hillocks, twenty or thirty feet 



D 2 



