8 THE POPULAR SCIENCE MONTHLY 



The chief sources of flint are the chalk deposits of Cretaceous age 

 that occur so plentifully in western Europe, as seen, for example, in the 

 white cliffs along the southern coast of England. Approaching one of 

 these cliffs, you will find it studded with parallel beds of flint nodules. 

 Wherever flint occurs stone-age relics are apt to be abundant. The 

 chalk of England, Belgium and northern France is the same age as the 

 flint-bearing calcareous deposits of Spain and southern France; but the 

 latter have not the white chalky appearance and are much harder; 



Fig. 4. Tkli.ikr Quarry, St. Aciieul. Third terrace. 



hence are full of caverns and rock shelters about which we shall speak 

 later. 



One great difficulty that confronts the student of human origins is 

 the paucity and fragmentary character of the evidence. This evidence 

 is limited to two kinds: skeletal and cultural remains. The first of 

 these is the rarest and at the same time the most incontrovertible. Xot 

 one complete skeleton has as yet been found. The less durable parts 

 are missing. The cranial cap, the lower jaw, a few teeth, bones of the 

 extremities, are the somatologist's chief sources of information. Except 

 in rare instances, the face bones and the base of the skull are missing. 



