vii THE ANTIQUITY AND ORIGIN OF MAN 417 



But this state of belief in opposition to facts could not 

 long continue. In 1859 a few of our most eminent geologists 

 examined for themselves into the alleged occurrence of flint 

 implements in the gravels of the north of France, which had 

 been made public fourteen years before, and found them 

 strictly correct. The caverns of Devonshire were about the 

 same time carefully examined by equally eminent observers, 

 and were found fully to bear out the statements of those 

 who had published their results eighteen years before. Flint 

 implements began to be found in all suitable localities in 

 the south of England, when carefully searched for, often in 

 gravels of equal antiquity with those of France. Caverns 

 giving evidence of human occupation at various remote 

 periods were explored in Belgium and the south of France 

 lake-dwellings were examined in Switzerland refuse-heaps in 

 Denmark and thus a whole series of remains have been 

 discovered carrying back the history of mankind from the 

 earliest historic periods to a long distant past. 



The antiquity of the races thus discovered cannot be 

 measured in years ; but it may be approximately determined 

 by the successively earlier and earlier stages of civilisation 

 through which we can trace them, and by the changes in 

 physical geography and of animal and vegetable life that 

 have since occurred. As we go back metals soon disappear, 

 and we find only tools and weapons of stone and of bone. 

 The stone weapons get ruder and ruder ; pottery, and then 

 the bone implements, cease to occur; and in the earliest 

 stage we find only chipped flints of rude design, though 

 still of unmistakably human workmanship. In like manner 

 domestic animals disappear as we go backward ; and though 

 the dog seems to have been the earliest, it is doubtful 

 whether the makers of the ruder flint implements of the 

 gravels possessed even this. Still more important as a 

 measure of time are the changes in the distribution of 

 animals, indicating changes of climate, which have occurred 

 during the human period. At a comparatively recent epoch 

 in the record of prehistoric times we find that the Baltic 

 was far salter than it is now and produced abundance of 

 oysters, and that Denmark was covered with pine 'forests 

 inhabited by Capercailzies, such as now only occur farther 

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