GENERAL FEATURES OF THE EARTH. 23 



but off in the remote west, on the broad Pacific, where they stand 

 open to the moist easterly winds as well as those of the west, to gather 

 rains and snows, and make rivers and alluvial plains for the continent; 

 and the waters of all the great streams, lakes, and seas make their 

 way eastward to the narrow ocean that divides the civilized world. 

 Europe has her slopes, rivers, and great seas opening into the same 

 ocean ; and even central Asia has her most natural outlet westward 

 to the Atlantic. Thus, under this simple law, the civilized world is 

 brought within one great country, the centre of which is the Atlantic, 

 uniting the land by a convenient ferriage, and the sides the slopes of 

 the Rocky Mountains and Andes on the west and the remote moun- 

 tains of Mongolia, India, and Abyssinia on the east. 1 



This subject affords an answer to the inquiry, What is a continent 

 as distinct from an island ? It is a body of land so large as to have 

 the typical basin-like form, — that is, mountain-borders about a low in- 

 terior. The mountain-borders of the continents vary from 500 to 

 1,000 miles in breadth at base. Hence a continent cannot be less 

 than a thousand miles (twice five hundred) in width. 



3. SYSTEM IN THE COURSES OF THE EARTH'S FEATURE- 

 LINES. 



The system in the courses of the earth's outlines is exhibited alike 

 over the oceans and continents, and all parts of the earth are thus 

 drawn together into even a closer relation than appears in the prin- 

 ciple already explained. 



The principles established by the facts are as follows : That (1) two 

 great systems of courses or trends prevail over the world, a north- 

 western and a northeastern, transverse to one another; (2) that the 

 islands of the oceans, the outlines and reliefs of the continents, and 

 the oceanic basins themselves, alike exemplify these systems ; (3) that 

 the mean or average directions of the two systems of trends are north- 

 west-by-west and northeast-by-north ; (4) that there are wide varia- 

 tions from these courses, but according to principle, and that these va- 

 riations are often along curving lines ; (5) that, whatever the variations, 

 when the lines of the two systems meet, they meet nearly at right 

 angles or transversely to one another. 



(1.) Islands of the Pacific Ocean. —The lines or ranges of islands 

 over the ocean are as regular and as long as the mountain-ranges of 

 the land. To judge correctly of the seeming irregularities, it is neces- 

 sary to consider that, in chains like the Rocky Mountains, or Andes, 

 or Appalachians, the ridges vary their course many degrees as they 

 continue on, sometimes sweeping around into some new direction, and 



1 See Guyot's Earth and Man. 



