Primitive Man. 55 



the most interesting being those found in the cretaceous or 

 chalk formation. As to the agencies by which they have 

 become thus filled with human and animal remains, the 

 action of river-floods does not appear to have been the sole 

 cause, though it may have been one of the most efficient. 

 As has been remarked, these cavities were, for a length of 

 time unknoAvn, utilized by primitive man, as well as by 

 various species of now mostly extinct animals, for purposes 

 of residence, and for temporary shelter ; both probably 

 carried or bore into them the animals upon which they 

 subsisted or preyed. The mere juxtaposition of human 

 and animal remains does not, of itself, demonstrate the 

 great antiquity of the former, for, in fact, various articles 

 of undoubtedly recent human workmanship have been 

 found thus associated. But '' doubt is no longer reasonable 

 when the bones of animals and those of our own species, 

 uniformly mixed, imbedded in the same sediment, and 

 which have undergone the same alterations both in external 

 characteristics and of chemical decomposition, are moreover 

 covered by a thick layer of stalagmite when objects of a 

 completely primitive industry occupy the same deposit 

 with bones of extinct fauna. And finally, when we find 

 in the diluvian strata of the valleys, manufactured objects 

 and bones exactly like those discovered in caves of the 

 same date, the proofs are conclusive." * 



Have we any data for determining or approximating the 

 age in the world's history of the glacial period, and there- 

 by the time of existence of the cave men and their prede- 

 cessors ? It seems that we have. I give the summary of the 

 argument as set forth by Professor Fiske, in his interesting 

 essay on the " Arrival of Man in Europe." The conclusions 

 there stated are those reached by Prof. Croll. The chief 

 cause of the reduction in temperature, Avhich ultimately 

 produced the ice age, was an alteration in the earth's orbit 

 in the direction of greater eccentricity. f It has been shown 

 that at least three times within the past 3,000,000 years 

 this eccentricity has reached its maximum, with the result 



* Prof. X. Joly, Man before Metals. 



t In the discussion followintr the lecture, Dr. P. H. van der Weyde sujifrested 

 that the gradual elevation of land-areas into the region of i)erpetual cold, was 

 a simpler and more reasonable explanation of the formerly extensive prev- 

 alence of glacial phenomena, which are still observable in areas of high eleva- 

 tion. This theory would require ecjually immense periods of time for the 

 deviation of these' recurrent periods of glacial action, and would equally indi- 

 cate the early appearance of man. 



