REPORT 



I. N. NICOLLET 



COLONEL J. J. ABERT, CHIEF OF THE CORPS OF TOPOGRAPHICAL 



ENGINEERS. 



PART I. 



PHYSICAL GEOGRAPHY OF THE REGION EMBRACED WITHIN THE MAP. 



The most remarkable feE^ture in the physical geography of North Amer- 

 ica is exhibited in its two systems of mountains ; the one to the west, 

 embracing the Mexican Ancles, and their prolongation northward, under 

 the name of the Rocky Mountains ; the other to the east, known as the 

 Alleghanies, or Apalachian chain. The wide expanse separating these 

 two systems of mountains, is considered as a vast plain that unites, as it 

 were, the Arctic ocean with the Gulf of Mexico. The irregularities of 

 this connecting region, viewed as an extensive whole, are so trifling, in a 

 topographical respect, that it can hardly be said to be diversified by moun- 

 tains, or even hills. Nevertheless, when examined by sections, it will be 

 found necessary, for the purposes of descriptive geography, to attend to 

 conventional distinctions ; so that, without departing from acknowledged 

 principles, I shall be obliged, according to circumstances, to speak of moun- 

 tains, hills, bluifs, mounds, eminences, plains, plateaux, <Scc. ; using these 

 expressions, however, always in reference to the comparative importance 

 of these irregularities as regards the country under description. Thus the 

 Washita chain, presenting summits that have not more than from 1,000 to 

 1,200 feet of elevation above the sea, or the champaign country at their 

 bases, have very appropriately received the name of the Washita moun- 

 tains ; whilst the mineral region of Missouri, the swellings of whose sur- 

 face attain nearly the s^me elevation in reference to the Mississippi, as the 

 former do to the ocean, are denominated the Missouri /lills. 



As to the region of country embraced within the limits of my map, its 

 topography differs entirely from that of the two mentioned. It is neither 

 a mountainous, nor a hilly, nor an absolutely flat country; exhibiting un- 

 dulations of the surface that are not entitled to these usual appellations. 

 There are hillocks, swells, and uplands ; but they have a longitudinal 

 and horizontal, rather than a vertical projection. In other words, it is 

 a beautiful arrangement of upland and lovirland plains, that give it an 

 aspect sui generis. The first Frenchmen who explored it, and the British 

 and Americans who followed them, were so forcibly impressed with this 



