278 THOUGHTS IN A GRAVEL-PIT. [xi. 



showing that there was dry land near ; and these trees, 

 as far as the best botanists can guess, were trees like 

 those we have in England now. Not of the same 

 species, of course : but still trees belonging to a tem- 

 perate climate, which had its regular warm summer 

 and cold winter. 



But before the London clay had been all deposited, 

 this temperate climate had changed to a tropical one ; 

 and the plants and animals of the upper part of the 

 London clay had begun to resemble rather those o 

 the mouths of the African slave-rivers. 



Extraordinary as this is, it is certainly true. 



We know that the country near the mouth of the 

 Thames, and probably the land round us here, was low 

 rich soil, some half under water, some overflowed by 

 rivers; some by fresh or brackish pools. We know 

 all this ; for we find the shells which belong to a shal- 

 low sea, mixed with fresh-water ones. We know, too, 

 that the climate of this rich lowland was a tropical 

 one. We know that the neighbourhood of the Isle of 

 Sheppey, at the mouth of the Thames, was covered 

 with rich tropic vegetation; with screw pines and 

 acacias, canes and gourds, tenanted by opossums, bats, 

 and vultures : that huge snakes twined themselves 

 along the ground, tortoises dived in the pools, and 

 crocodiles basked on the muds, while the neighbouring 

 seas swarmed with sharks as huge and terrible as those 

 of a West Indian shore. 



It is all very wonderful, ladies and gentlemen : but 

 so it is : and all we can say is, with the Mussulman 

 " God is great." 



And then when, none knows but God there came 



