UNITED STATES. 



115 



about one half of wliich consists of the elevation of the mountains above their base, and the other 

 of the elevation of the adjoining country above the sea. To this height the country rises, by 

 an almost imperceptible acclivity, from the ocean, at the distance of 200 or 300 miles on the 

 one side, and from the channel of the Mississippi, at an equal distance, on the other. A grad- 

 ual elevation of 1,000 or 1,200 feet upon a horizontal surface of 200 or SOO miles, would give 

 the surface of the country, on the eastern side, an average rise of from 3 to 4 feet in the mile, and 

 from 2 to 3 feet on the western side. This small degree of inclination accounts for the great 

 extent of inland navigation which the United States enjoy. By the course of the Mississippi, 

 Ohio, and Alleghany rivers, vessels ascend over an inclined plane of 2,400 miles in extent, to 

 an elevation of perhaps 1,200 or 1,400 feet, without the help of canals or locks. 



(2.) The second great mountainous range which traverses the United States, is the Rocky 

 Mountains. This ridge is more elevated than the former, but is also more distant from, the 

 Pacific Ocean on the one side, and the Mississippi on the other. From the Mississippi to the 

 Pacific, in latitude 40^, is about 1,500 miles ; and the Rocky Mountains, which crown this 

 graduall}^ swehing surface, rise, with the exception of some insulated peaks, to a height of 

 about 9,000 feet. This elevation is about three times as great as that of the Alleghanies ; and 

 it is remarkable that the Mississippi, the common reservoir of the streams descending from both, 

 is about three times further from the higher chain than from the lower, so that the declivity on 

 both sides of the immense basin included between these mountains, is nearly the same ; and the 

 streams flowing from the Rocky Mountains are as susceptible of navigation as those from the 

 Alleghanies. 



The Mississippi valley also presents a southern declivity, by which it gradually sinks from 

 the high table-land of the centre of the continent to the level of the ocean on the Gulf of Mex- 

 ico. From this table-land, which is estimated to have an elevation of not more than 1,500 

 feet above the sea, descend the great rivers of North America, — Mackenzie's to the north, the 

 St. Lawrence to the east, and the Mississippi to the south. 



(3.) To the west of the Rocky Mountains hes the Pacific slope, the declivity of which is 

 greater and more rapid than those of the others. This region, as yet little known, is visited 

 only by missionaries, hunters, and trading ships. 



3. Soil. With regard to soil, the territory of the United States to the east of the Rocky 



Mountains may be classed un- 

 der five grand divisions : 



(1.) That of the New England 

 States, east of the Hudson, 

 where the Alleghanies spread 

 out into a broken, hilly country. 

 The soil is here, in general, 

 rocky, has but little depth, is 

 barren in many places, and bet- 

 ter adapted for pasture than til- 

 lage. 



(2.) The sandy soil of the sea- 

 shore, commencing from Long 

 Island, and extending along the 

 coast of the Atlantic and the 

 Gulf of Mexico to the mouth of 

 the Mississippi, with a breadth 

 varying from 30 to 100 miles. 

 This tract, from the Potomac 

 southward, approaches to a horizontal plain, very httle raised above the sea, and traversed 

 through its whole breadth by the tide water at the mouths of the great rivers. The surface, 

 which consists of sea sand, is scarcely capable of cultivation, and produces nothing but pines, 

 except on the banks of rivers, and in marshy spots where rice is raised. 



(3.) The land from the upper margin of this sandy tract to the foot of the Alleghany moun- 

 tains, from I'D to 200 miles in breadth, the soil of which is generally formed from the alluvion 

 of the mountains, and the decomposition of the primitive rocks beneath the surface. This 

 tract is fertile, and generally well adapted for tillage. 



