OF CREATION. 227 



CHAPTER X. 



THE INHABITANTS OF THE EARTH DURING THE CRETACEOUS 

 PERIOD. 



THE newest portion of the great middle epoch com- 

 menced soon after the termination of the deposits 

 from that great river whose delta formed the Weald 

 of Kent and Sussex, and traces of whose existence 

 we find also in the Isle of Wight and on the coast of 

 France near Boulogne. In the south-east of England, 

 by a gradual depression of small amount, a great 

 tract, once the recipient of fresh water, sunk down 

 and became once more subject to marine deposits. 

 This being the case, it is not wonderful that a great 

 change also took place in the nature of the fossils, and 

 that the whole of the fresh- water species disappeared, 

 and were replaced by others adapted to the new and 

 changed condition of things. A modification of this 

 kind extended also over a wide area, reaching from 

 England to the Caucasus, and perhaps continuing as 

 far as southern India : a new series of animals came 

 into existence throughout the district, while a con- 

 stant succession of alterations of the level of the sea- 

 bottom sometimes produced slight elevations, but 

 more frequently, and on the whole, considerable de- 

 pression. In this way was marked the commence- 

 ment of the new period, and during the early part 

 of it the deposit of the bed called "lower green- 



