FL(ETZ TRAP FOltMATlOXS. 198 



rallclisin with the liorizon. The slia;ht inequalities of the sur- 

 fiicc arc often manifestly the effects of water, which running 

 forages over a ligiit and loose soil, have hollowed for them- 

 selves channels and valleys proportioned to their size and 

 velocity. Wherever these currents, or other causes, have 

 laid hare the rocky substrata of the soil, the remains of ma- 

 rine animals are found incorporated in the boily of the rf)clv. 

 They are also met with in most perfect preservation in the 

 soil. 



These appearances aftoid suflicicnt cvidenrc. that at some 

 remote period the waters of the ocean rested ui)on tliis ex- 

 tensive region. 



Proccechng westward from the Mississippi, the surface 

 rises gradually, having however inclination sufficient to give 

 to many of the streams which traverse tliat part of the coun- 

 try a velocity of near six miles per hour. This inclination 

 seems to Ije greatest in tlie neigiibourhood of tlie Missouri, 

 as that river, the Quicurre, Platte, ^*c. have a much more 

 rapiil current tiian tlie Arkansaw and the south western tribu- 

 taries of the Mississippi. The country bordering on the 

 Mississippi is for the most part deeply covered with soil, 

 whicli supports a profuse vegetation. To tlic north and 

 west it differs little from one extensive savanna. The tra- 

 veller Journeys, for weeks in succession, over a dreary and 

 monotonous plain, sparingly skirted and striped with narrow 

 undulating lines of timber, which grow only along tlie mar- 

 gins of considerable streams of water. In these boundless 

 oceans of grass, his sensations are not unlike those of the 

 mariner, who beholds around him only the expanse of the 

 sky and the waste of waters. 



The Missouri, between the Mississippi and the mouth of 

 the Platte, passes through some considcral)!y extensive fields 

 of com|)act limestone, sandstone, and other horizontally stra- 

 tilled rocks. On tlic Platte, no rocky formations aj)pear 

 within about four hundred miles from its confluence with 

 the Missouri. At about this distance, some inconsiderable 



