CONCLUDING REMARKS. 91 



very great antiquity can be assigned to tlie dense forests of Wisconsin ; for during 

 a long period of time, with no material change of cUuiate, we wouki expect to find 



Fig. hi. 

 XVK JiYH ^^ ^^ 



-L# -It 



Map showing '• WinJ-fiiUs," reported by the Surveyors of the rublic Lands. Si.x miles to one inch 



great numbers of these Httle monuments of ancient storms scattered every where 

 over the ground. 



Whether the greater extent of treeless country in former times was owing to 

 natural or artificial causes, it is now difficult to determine ; but the great extent 

 of ancient works within the depths of the present forests, would seem to indicate 

 that the country was at least kept free from trees by the agency of- man. 



Many of these tree-mounds were observed on and about the ancient works. 



Another curious circumstance that may be noticed by inspection of the figures of 

 mounds accompanying this work, is the gradual transition, as it were, or change of 

 one form into another. Examples can be found of all forms, from a true circle, 

 through the oval and elongated oval, to the oblong mounds and long ridges. 

 Again, there is a succession of mounds, from the simple ridge of considerable size at 

 one end, and gradually diminishing to a point at the other, through the intermediate 

 forms, having one, two, three, or four projections, to the " turtle form." In this 

 way, also, we may trace a gradual development (so to f*poal<) of iionrl}- all the 

 more complicated forms. 



It is not pretended to assert that this was the order in which the mounds were 

 erected; or that the aborigines gradually acquired the art by successive essays or 



