206 IDE STORY OF THE EARTII AND MAN. 



other lines of evidence which would reduce the resi- 

 dence of man in America to a much shorter time. 

 Longer periods have, it is true, been deduced from 

 the delta of the Mississippi and the gorge of Niagara ; 

 but the deposits of the former have been found by 

 Hilgard to be in great part marine, and the exca- 

 vation of the latter began at a period probably long 

 anterior to the advent of man. 



But another question remains. From the simi- 

 larities existing in the animals and plants of regions 

 in the southern hemisphere now widely separated by 

 the ocean, it has been inferred that Post-pliocene 

 Lmd of great extent existed there ; and that on this 

 land men may have lived before the continents of 

 the northern hemisphere were ready for them. It 

 has even been supposed that, inasmuch as the flora 

 and fauna of Australia have an aspect like that of the 

 Eocene Tertiary, and very low forms of man exist 

 in that part of the world, these low races are the 

 oldest of all, and may date from Tertiary times. 

 Positive evidence of this, however, there is none. 

 These races have no monuments ; nor, so far as 

 known, have they left their remains in Post-pliocene 

 deposits. It depends on the assumptions that the 

 ruder races of men are the oldest; and that man 

 has no greater migratory powers than other animals. 

 The first is probably false, as being contrary to 

 history; and also to the testimony of palaeontology 

 with reference to the laws of creation. The second 

 is certainly false ; for we know that man has managed 



