PHYSICAL GEOGRAPHY. 8 



This country has some vciy pecuhar natural features. 

 The most remarkable ui these is the innimicrable multitude 

 of lakes that spangle its northern surface, the remains, no 

 doubt, of a vast sea that once covered the whole country 

 extending north from the ihiU of Mexico, and perhaps reach- 

 ing to Hudson's Bay. 



Besides this, there arc two great natural features belong- 

 ing to the Valley of the Upper Missisippi, which perhaps 

 are never fully realized but by actual inspection. The first 

 consists in the uniformity of elevation, and the shape of the 

 surface. The countr}^, from the outlets of the Illinois and 

 Missouri to St. Peter's, and from the Lake Michigan to 

 Council BlulTs, and beyond that point westerly, is a vast 

 plain, slightly inclining, ascending to the north and to the 

 west. By observations taken between the Missisippi and 

 the Lake, the elevation above the Atlantic has been found a 

 little exceeding 500 feet : and west of the river, in the same 

 parallel, toward the Missouri, something over 700 feet. At 

 St. Peter's it is about 700. Nicollet states, as the result 

 of over one hundred observations taken at Camp Kearney, 

 near Council Bluffs, that that point is 1037 feet above the 

 Gulf ; and the elevation of Rock Island, in the same lati- 

 tude, on the Missisippi, he says, is 528 ; and the hciglit of 

 Fort Pierre Chouteau, uii the Missouri, he states at 1456 ; 

 and the lower end of Lake Pepin, in the same latitude (44*^ 

 24'), 710. The mouth of St Peter's, in about latitude 45°, 

 744 feet. Tliere are a few elevations above the general 

 range, called mounds : but witli tlie exception of these, the 

 surface is marked only by ravines running from the general 

 level down to the beds of tlie streams, which are usually 

 from 100 to 200 feet lower. 



The other remarkable prominent feature is the vegetable 

 covering of the surface. There are large tracts of country 



