246 THE STORY OF THE EAETH AND MAN. 



ing shores, and they show first the elevation of tho old 

 deep-sea bottom represented by the chalk, so that part 

 of it became dry land ; next, the peopling of that land 

 by tribes of animals and plants unknown to the Meso- 

 zoic ; and lastly, that a warm climate must have existed, 

 enabling England at this time to support many types 

 of animals and plants now proper to intertropical 

 regions. As Lyell well remarks, it is most interesting 

 to observe that these beds belong to the beginning 

 of the Tertiary, that they are older than those great 

 nummulite limestones to which we have referred, and 

 that they are older than the principal mountain chains 

 of Europe and Asia. They show that no sooner was 

 the Cretaceous sea dried from off the new land, than 

 there were abundance of animals and plants ready to 

 occupy it, and these not the survivors of the flora and 

 fauna of the Wealden, but a new creation. The men- 

 tion of the deposit last named places this in a striking 

 light. We have seen that the Wealden beds, under 

 the chalk, represent a Mesozoic estuary, and in it we 

 have the remains of the animals and plants of the laud 

 that then was. The great Cretaceous subsidence inter- 

 vened, and in the London clay we have an estuary of 

 the Eocene. But if we pass through the galleries of 

 a museum where these formations are represented, 

 though we know that both existed in the same locality 

 under a warm climate, we see that they belong to two 

 different worlds, the one to that of the Dinosaurs, the 

 Ammonites, the Cycads, and the minute Marsupials of 

 the Mesozoic, the other to that of the Pachyderms, the 

 Palms, and the Nautili of the Tertiary. 



