75 



in their development and even to assign the approxi- 

 mate years during which each was in vogue. The rough 



Prom Birkner, " Dcr Diluviale Mensch in Europa." 



FIGURE 29. Flint Implements of the Acheulian Epoch. 



stone age and the polished stone age are the popular 

 terms for the stages showing the most striking differences 

 in appearance and workmanship. In figure 14 the 

 most recent geologic epoch, the Quaternary, is divided 

 into the lower, middle, and upper Quaternary, covering 

 a period of some 750,000 years. It will be noticed that 



