202 The Development Theory. 



ceous, Eocene, Miocene, Pliocene, Post Ter- 

 tiary, each one of these names representing in 

 succession a period of time and an area added 

 to the continent. They stand toward each 

 other in three lines of relationship. First, they 

 stand toward each other in the relation of 

 parts to a whole continent, each part in such 

 relation to the whole that it could not possibly 

 fit anywhere else. Second, they stand to each 

 other and to the whole in the relation of suc- 

 cession in history. In this relation to the 

 whole continent the place of each period is as 

 necessarily where it is as that of a part to the 

 whole. The third relation is that of deriva- 

 tion. As before stated, each successive addi- 

 tion to the continent was an off-shore sea bed 

 near the former land, the muddy sediment of 

 which had been for ages wearing from the up- 

 lands; had been carried to the sea by neigh- 

 boring rivers and distributed by tides and cur- 

 rents; had at length been elevated into dry 

 land to form another, an added field, to our 

 continental form. Thus it was that each 

 added area was derived from the eroded sur- 



