PART 11. 



CHAPTER XIX. 

 DESCRIPTIVE GEOLOGY. 



PHYSICAL GEOGRAPHY OF NORTH AMERICA. 



Extent of North America. — Mountains. — Rocky Mountains.-— 

 Atlantic Series.— The Blue Ridge. — The Appalachian, — The 

 Alleghany. — The Eastern System. — Atlantic Plain. — Central 

 Basin.— Influence of Geological Structure on Society. — Influ- 

 ence of Geological Formations on Scenery. 



Physical Geographj. — Before treating of the ge- 

 ology of this country, which our limits will only 

 allow us to do in a very brief and cursory manner, 

 it will be proper to notice some of its grand geo- 

 graphical features ; and, Xn doing so, we shall not 

 confine our attention to the United States, but em- 

 brace the whole of North America. This extends 

 through twenty-nine degrees of latitude and fifty- 

 eight of longitude, comprising a superficial area of 

 2,300,000 square miles, and having a frontier line of 

 10,000 miles in length, 3600 of which are seacoast 

 and 1200 lakecoast; and a line drawn from the Pa- 

 cific to the A tlantic, in its widest part, would be 

 more than 2500 miles long. The portion at present 

 organized into state governments comprises an area 

 of 1,300,000 square miles. 



Nortl^America* is traversed by two great mount- 



* For much of the following chapter we are indebted to the 

 American edition of the " Encyclopedia of Geography," pub- 

 lished in Philadelphia, and the best work of the kind that has 

 ever appeared. ^ 



