Formation of Continents and Oceanic depressions. 169 
7. The Continents always the continental areas. 
The above-stated effects of contraction lead to the necessary 
conclusion that the oceanic and continental areas were defined 
when the earth’s crust first began to form, if not also still 
earlier, during the progress of its nucleal solidification. It is 
the continental plateaus should have varied greatly in their out- 
ines and outer limits, and perhaps thousands of feet in the 
depth of some portions of the overlying seas; and also that the 
oceans should have varied in the extent of their lands. The 
any characteristics of the continental borders: for example, 
the contrast between the landward and seaward slopes of the 
Mountains, and even of the plications constituting them, the 
* This Journal, II, iii, 381, 1847. 
