PHYSICAL FEATURES OF THE UNITED STATES 311 



characters of the United States, and for this purpose it is conven- 

 ient to divide the country into a few broad provinces. 



Parallel to the Atlantic coast is the Appalachian Mountain 

 belt, running northeastward from Alabama to New England. 

 East of it lies the Atlantic plain. West of it the Central plain, 

 consisting lai'gely of the valley of the Mississippi, stretches to 

 the base of the Rocky mountains. Thence to the Pacific coast 

 is a mountainous province known to geographers as the Cordil- 

 leras. A fifth province, the •province of the Lakes, overlaps the 

 northern portions of the other four and reaches from ocean to 

 ocean along our Canadian border. 



The Cordilleran province, comprising the western third of our 

 country, is characterized hy mountain ranges. The dominant 

 trend is with the meridian, swerving in some districts toward 

 the southeast, and in others toward the southwest; and in each 

 district there is a general parallelism. The ranges are definitely 

 Plutonic, each one having been caused by a distinct local uplift ; 

 but they are not altogether independent, for there is much evi- 

 dence of system in their arrangement. Not only are neighbor- 

 ing ranges approximately parallel, but they are evenly spaced, 

 so that in crossing the system one finds a regular alternation of 

 ridge and valley. Through extensive districts the alluvial waste 

 from the erosion and sculpture of the ranges is gathered in the 

 intervening valleys, making of each one a shallow basin or gently 

 concave plain, where roads may run at will. Here and there 

 some of the lower ranges are almost buried by the alluvial fill- 

 ing, so that their summits project as craggy islands above a 

 sea of rock waste. Elsewhere, and especially where the moun- 

 tains are highest, the intervening valleys are drained by vigorous 

 rivers, which carry off the waste and prevent the building of ex- 

 tensive plains. In one important district uplift lias not com- 

 pleted its work of mountain-making, and the land forms a system 

 of plateaus of various heights, through which the Colorado and 

 its tributaries have carved their wonderful system of canyons. 

 Volcanoes, also, have made extensive contributions to the topog- 

 raphy, building many great cones and a multitude of cratered 

 hills, and adding voluminous beds of lava to the alluvial strata 

 of the valleys. 



In the extreme northwest the rainfall is exceptionally abundant, 

 causing a forest growth so luxuriant and dense that the farmer 

 cannot afford the labor of its subjugation as the purchase price 

 to Nature for his land. Much of this district, also, is too rugged 



