PAET I. 

 PHYSIOGRAPHIC GEOLOGY. 



The systematic arrangement in the earth's features is every way as 

 marked as that of any organic species ; and this system over the exte- 

 rior is an expression of the laws of structure beneath. The oceanic 

 depressions or basins, with their ranges of islands, and the continental 

 plains and elevations, all in orderly plan, are the ultimate results in 

 the whole line of progress of the earth ; and, by their very compre- 

 hensiveness as the earth's great feature-marks, they indicate the pro- 

 foundest and most comprehensive movements in the forming sphere, 

 just as the exterior configuration of an animal indicates its interior 

 history- This subject is therefore an important one to the geologist, 

 although its facts come also within the domain of physical geography. 

 They lie at the top in geology as its last results, and, thus situated, 

 constitute necessarily the arena of the physical geographer. 



The following are the divisions in this department : — 



1. The earth's general contour and surface-subdivisions. 



2. System in the reliefs or surface-forms of the continental lands. 



3. System in the courses of the earth's feature-lines. 

 These topics are followed by a brief review of, — 



4. The system of oceanic movements and temperature. 



5. The system of atmospheric movements and temperature. 



6. The general law for the distribution of forest-regions, prairies, 

 and deserts. 



1. THE EARTH'S GENERAL CONTOUR AND SURFACE- 

 SUBDIVISIONS. 



The subjects under this head are — the earth's form ; the distribu- 

 tion of land and water ; the depth and true outlines of the oceanic 

 depression ; the subdivision of the land into continents ; the height and 

 kinds of surface of the continents. 



(1.) Spheroidal form. — The earth has the form of a sphere with 

 fattened poles, the distance from the centre to the pole being about 



