204 GREAT ANTIQUITY OF NATCHEZ LOAM. chap. xi. 



basin of the Mississippi as is the Cyrena fluminalis to the 

 rivers of modern Europe. If, therefore, the rehitive ages of 

 the Picardy and JSTatchez aUuviura were to be decided on 

 conehological data alone, the flavio-marine beds of Abbeville 

 might rank as a shade older than the loess of Natchez. My 

 reluctance in 1846 to regard the fossil human bone as of post- 

 pliocene date arose in part from the reflection that the ancient 

 loess of Natchez is anterior in time to the whole modern 

 delta of the Mississippi. The table-land, d e, fig. 26, p. 200, 

 was, I believe, once a part of the oi'iginal alluvial plain or 

 delta of the great river before it was upraised. It has now 

 risen more than two hundred feet above its pristine level. 

 After the upheaval, or during it, the Mississippi cut through 

 the old fluviatile formation of which its bluffs are now 

 formed, just as the Rhine has in many parts of its valley ex- 

 cavated a passage through its ancient loess. If I was right 

 in calculating that the present delta of the Mississippi has 

 required, as a minimum of time, more than one hundi'ed 

 thousand years for its growth,* it would follow, if the claims 

 of the Natchez man to have coexisted with the mastodon are 

 admitted, that North America was peopled more than a thou- 

 sand centuries ago by the human race. But, even were that 

 true, we could not presume, reasoning from ascertained geo- 

 logical data, that the Natchez bone was anterior in date to 

 the antique flint hatchets of St. Acheul. When we ascend 

 the Mississippi from Natchez to Vicksburg, and then enter 

 the Ohio, we are accompanied everywhere by a continuous 

 fringe of terraces of sand and gravel at a certain height above 

 the alluvial plain, first of the great river, and then of its 

 tributary. We also find that the older alluvium contains the 

 remains of mastodon everywhere, and in some places, as at 

 Evansville, those of the megalonj'x. As in the valley of the 

 Somme in Europe, those old post-pliocene gravels often occur 



* Seo Principles of Geology. 



