APPENDIX 



REFERENCE-LIST, NOTES, AND BIBLIOGRAPHIES 

 CHAPTER I 



PREHISTORIC SCIENCE 



Length of the Prehistoric Period. It is of course quite im- 

 possible to reduce the prehistoric period to any definite 

 number of years. There are, however, numerous bits of 

 evidence that enable an anthropologist to make rough esti- 

 mates as to the relative lengths of the different periods into 

 which prehistoric time is divided. Gabriel de Mortillet, one 

 of the most industrious students of prehistoric archaeology, 

 ventured to give a tentative estimate as to the numbers of 

 years involved in each period. He of course claimed for this 

 nothing more than the value of a scientific guess. It is, how- 

 ever, a guess based on a very careful study of all data at pres- 

 ent available. Mortillet divides the prehistoric period, as a 

 whole, into four epochs. The first of these is the preglacial, 

 which he estimates as comprising seventy-eight thousand 

 years; the second is the glacial, covering one hundred thou- 

 sand years; then follows what he terms the Solutre'en, which 

 numbers eleven thousand years; and, finally, the Magdal6nien, 

 comprising thirty-three thousand years. This gives, for the 

 prehistoric period proper, a term of about two hundred and 

 twenty-two thousand years. Add to this perhaps twelve 

 thousand years ushering in the civilization of Egypt, and the 

 six thousand years of stable, sure chronology of the historical 

 period, and we have something like two hundred and thirty 

 thousand or two hundred and forty thousand years as the 

 age of man. 



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