INDICATIONS OF FOUR PERIODS. 285 



can tribes developed a knowledge of agriculture and a power 

 of combination. 



2. That in which for the first time mounds were erected, 

 and other great works undertaken. 



3. The age of the "garden-beds," which occupy some at 

 least of the mounds. Hence it is probable that these par- 

 ticular "garden-beds" were not in use until after the mounds 

 had lost their sacred character in the eyes of the occupants of 

 the soil ; for it can hardly be supposed that works executed 

 with so much care would be thus desecrated by their builders. 



4. The period in which man relapsed into partial barbarism, 

 and the spots which had been first forest, then, perhaps, sacred 

 monuments, and thirdly, cultivated ground, relapsed into forest 

 once more. 



But even if we attribute to these changes all the importance 

 which has ever been claimed for them, they will not require 

 an antiquity of more than three thousand years. I do not, 

 of course, deny that the period may have been, and in all 

 probability was, very much greater. There are, moreover, 

 other observations, which appear to indicate a very much 

 higher antiquity. 



Dr. A. C. Koch* records the case of a mastodon found in 

 Gasconade County, Missouri, which had apparently been 

 stoned to death by the Indians, and then partially consumed 

 by fire. 



The same writer mentions a second case in which several 

 stone arrow-heads were found mingled with the bones of a 

 mastodon. These statements, however, are not generally ac- 

 cepted by geologists, and the evidence in support of them is, 

 to say the least, very doubtful. 



In the valley of the Mississippi, Dr. Dickeson, of Natchez, 

 found the os innominatum of a man with some bones of the 

 Mastodon ohioticus, which had fallen from the side of a cliff 

 * Trans, of the Academy of Science of St. Louis, 1857, p. 61. 



