CHAP. XI. AGE OF NATCHEZ FOSSIL MAN. 205 



at more than one level, and the ancient mounds of the Ohio, 

 with their works of art, described at p. 39, are newer than 

 the old terraces of the mastodon period, just as the G-allo- 

 Eoman tombs of St. Acheul or the Celtic weapons of the 

 Abbeville peat are more modern than the tools of the mam- 

 moth-bearing alluvium. 



In the first place, I may remind the reader that the vertical 

 movement of two hundred and fifty feet, required to elevate 

 the loess of Natchez to its present height, is exceeded by the 

 upheaval which the marine stratum of Cagliari, containing 

 pottery, has been ascertained by Count de la Marmora to 

 have experienced, p. 177. Such changes of level, therefore, 

 have actually occurred in Europe in the human epoch, and 

 may therefore have happened in America. In the second 

 place, I may observe that, if, since the Natchez mastodon was 

 imbedded in clay, the delta of the Mississippi has been 

 formed, so, since the mammoth and rhinoceros of Abbeville 

 and Amiens were enveloped in fluviatile mud and gravel, to- 

 gether with flint tools, a great thickness of peat has accumu- 

 lated in the valley of the Somme ■ and antecedently to the 

 first growth of peat there had been time for the extinction 

 of a. great many mammalia, requiring, perhaps, as shown at 

 p. 144, a lapse of ages many times greater than that de- 

 manded for the formation of thirty feet of peat, for since the 

 earliest growth of the latter there has been no change in the 

 species of mammalia in Europe. 



Should future researches, therefore, confirm the opinion 

 that the Natchez man coexisted with the mastodon, it would 

 not enhance the value of the geological evidence in favor of 

 man's antiquity, but merely render the delta of the Missis- 

 sippi available as a chronometer, by which the lapse of post- 

 pliocene time could be measured somewhat less vaguely than 

 by any means of measuring which have as yet been dis- 

 covered or rendered available in Europe. 



