26 THE PLAINS. 



nately the most dangerous sands are moderately firm on 

 the surface, and a man has usually sufficient warning to 

 enable him, with ordinary presence of mind, to escape. 

 Besides this, from his broader foot and quicker move- 

 ments, a man does not sink in quicksands so rapidly as a 

 horse or mule, and men will walk with impunity around 

 a waggon sunk to its bed, or drag out a mule sunk to its 

 haunches. 



The streams which take their rise in the second plain, 

 as the Loup, the Republican, Smoky, and the more 

 easterly tributaries of the great rivers, have nearly the 

 same peculiarities as their more ambitious compeers. At 

 their heads they round off the broad expanse into long 

 slopes. Gradually deepening, they cut their way through 

 more or less pretentious canons, with narrow, fertile, 

 alluvial bottoms, gorged with vegetation, charming in 

 grace of outline, and beautiful in variety of scenery. 

 On arriving at the third plain, they take the characteris- 

 tics of the larger rivers in that plain, and, on a smaller 

 scale, are just as bare, as monotonous, and as dangerous. 

 This third plain was probably once the almost desert 

 shore of a shallow sea, or arm of the Gulf of Mexico, 

 into which was poured the rich treasures of alluvial soil 

 brought from the mountains, gradually filling it up and 

 forming a great marsh. It is the most barren and least in- 

 teresting of the plains, and sinks gradually towards the east 

 and south, becoming finally merged in that great alluvial 

 deposit now the Mississippi Valley proper. The transition 

 from the bare, sandy monotony of the one, to the luxu- 

 riant, almost tropical, vegetation of the other, is generally 

 too gradual to be fully appreciated. Occasionally, how- 

 ever, it is so abrupt as to be almost startling, giving rise 

 to a thousand conjectures as to the cause of the remark- 

 able phenomenon. 



I have heretofore intimated that there are no really 

 level plains. This is a truth to which there are exceptions. 

 Portions of the surface of the great first plain, within the 



