The Development Theory. 201 



Our own continent began its history as 

 such, eons ago, as a long strip of elevated sea 

 bed extending westward and northward from 

 our present Labrador. To this nucleus were 

 added through long periods of time, and by 

 the natural agencies of flood and tide and the 

 life and death of plant and animal, successive 

 strips of land, each strip having at once a 

 separate history of its own and a wider histor- 

 ical connection with the whole continent. So 

 plainly is this true that the whole geological 

 history is now conceded to be a marked in- 

 stance of a grand system of development 

 with plan and purpose in its movements, al- 

 though conducted through ages of change 

 and the agencies of nature. 



Age after age thus left their record until 

 our continent reached its present southern ex- 

 tension in Florida and the gulf coast, and its 

 western extension along the shores of our 

 coast range of the Pacific. To these succes- 

 sive areas added to the continent geologists 

 have applied the names Laurentian, Silurian, 

 Devonian, Carboniferous, Jurassic, Creta- 



