DIFFICULTIES OF DEVELOPMENT, ETC. 61 



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 dis- 

 covered, carrying back the history of mankind from the earliest his- 

 toric periods to a long-distant past. The antiquity of the races thus 

 discovered can only be generally determined by the successively ear- 

 lier and earlier stages through which we can trace them. As we go 

 back, metals soon disappear, and we find only tools and weapons of 

 stone and of bone. Tbe 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 un- 

 mistakably 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 of the earth's surface of the 

 distribution of animals and 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 north in Norway. A little earlier we find that reindeer were 

 common even in the south of France, and still earlier this animal was 

 accompanied by the mammoth and woolly rhinoceros, by the arctic 

 glutton, and by huge bears and lions of extinct species. The presence 

 of such animals implies a change of climate, and both in the caves 

 and gravels we find proofs of a much colder climate than now prevails 

 in Western Europe. Still more remarkable are the changes of the 

 earth's surface which have been effected during man's occupation of 

 it. Many extensive valleys in England and France are believed by 

 the best observers to have been deepened at least a hundred feet; 

 caverns now far out of the reach of any stream must for a long suc- 

 cession of years have had streams flowing through them, at least in 

 times of floods and this often implies that vast masses of solid rock 

 have since been worn away. In Sardinia land has risen at least three 

 hundred feet since men lived there who made pottery and probably 

 used fishing-nets ; ' while in Kent's Cavern remains of man are found 

 buried beneath two separate beds of stalagmite, each having a distinct 

 texture, and each covering a deposit of cave-earth having well-marked 

 differential characters, while each contains a distinct assemblage of 

 extinct animals. 



Such, briefly, are the results of the evidence that has been rapidly 



accumulating for about fifteen years as to the antiquity of man ; and 



it has been confirmed by so many discoveries of a like nature in all 



parts of the globe, and especially by the comparison of the tools and 



1 Lyell's "Antiquity of Man," fourth edition, p. 115. 



