284 PHYSIOGRAPHY. [chap. 



members of the old fauna. Thus, the collection of Sir 

 Antonio Brady contains portions of no fev^er than a hundred 

 elephants, all collected from the brick-earth of Ilford. 



Such, then, is the curious assemblage of animals which 

 fed at one time in the valley of the Thames, and have left 

 their bones and teeth in the ancient deposits of the river. 

 Some of these mammals have since died out, and are no 

 longer to be found in any part of the world ; others have 

 wandered to the south ; while others, again, have retreated 

 northwards, a few, however, still remaining in the present 

 fauna of the country. The strange association, in the same 

 deposit, of both northern and southern forms — tiiese in- 

 dicating a warmer, and those a colder climate — offers per- 

 plexing evidence as to the climatic condition of the country 

 at the time in which they lived. It is certain, however, that 

 at one time, the climate of the Thames basin must have 

 been extremely severe, since some of the deposits in the 

 northern districts present unmistakable evidence of the 

 prevalence of glacial conditions (p. 165). Evidence of the 

 kind given in Chapter X. shows that there must have been a 

 time when Britain, north of the Thames, was covered either 

 with land-ice, or with an icy sea, from which the boulder clay 

 and glacial gravels were deposited. Possibly, some of the 

 gravel in the Thames basin may be glacial drift, which has 

 been disturbed and re-deposited by the river. And, it should 

 be mentioned, that the remains of the reindeer are abundant 

 in many of the superficial deposits of the Thames valley, 

 though not in the brick-earth, which has yielded so many of 

 the fossils previously noticed. Indeed, the relation of this 

 brick-earth to the glacial period is by no means clear ; some 

 geologists believing it to be more, and others less, recent 

 than the true glacial drifts. 



It becomes an extremely interesting question to determine 



