Some Considerations on the Mound Builders. 63 



of the works upon the upper Missouri. These are, I 

 believe, the oldest that have been observed. 



Many two hundred and four hundred years have 

 been noted. In many cases the forest appears more re- 

 cent. Judge A. H. Dunlevy, of Lebanon, in a letter 

 to the Historical Society in this city, said that he had 

 noted in the woods upon Fort Ancient an entire ab- 

 sence of the little hillocks, formed by earth about the 

 roots of a tree that is blown down and uprooted. 

 When the tree decays, the uprooted soil forms a knob 

 or hillock, and such are always seen in old forests. 

 From their absence he infers that the woods upon Fort 

 Ancient are the original growth. Professor Lapham 

 made the same observation, and drew the same inference 

 as to forest growth covering a great part of the remains 

 in Wisconsin. The very aged trees, six hundred or 

 more years old, found on some mounds are, then, prob- 

 ably the survivors of the original forest growth on 

 those mounds, and had attained respectable maturity 

 while other mounds were still bare. No lone interval 

 would elapse after the abandonment of the earthworks 

 before trees would spring up. Making full allowance 

 for this interval, and for the growth and disappearance 

 of preliminary weeds and shrubs, the forest growth 

 does not indicate an abandonment of any of the mounds 

 at a period more remote than a thousand years, and 

 many of them may have been occupied or used by their 

 builders up to a much later date. The extinction or 

 disappearance of the Mound Builders may, therefore, 

 reasonably be said to have begun about a thousand 

 years ago, and to have been gradual, and not to have 

 been completed until near the discovery of the conti- 

 nent by Columbus. 



