AKROW-SMOOTHENERS. 53 



Most, if not all, of these grindstones are made from 

 the Dakota sandstone. Specially indurated blocks have 

 been selected. The metates have not all been dressed 

 to their present form. A few appear to be merely 

 broken, oblong, irregularly rectangular Jblocks, worn 

 smooth on ona side. More pains were taken with the 

 hand grinders. Some slightly worn specimens of these 

 show the pick marks of the dressing tool, whatever 

 that may have been. Other ones have been further 

 smoothened by special grinding or by wear in use. 

 Several specimens bear the mark of long continued ser- 

 vice, as do also most of the metates. A thickness of 

 nearly two inches has been ground off from the upper 

 face of some of the latter, and fi-om the form of some 

 of the hand stones we must infer that these have been 

 reduced by nearly half of that thickness. There can be 

 no doubt that these stones were used for grinding corn. 

 Their number and condition testif3^ that this grain 

 was an important part of the food among the natives 

 who used them. It is quite evident that these people 

 must have had some knowledge of agriculture. 



ARROW-SMOOTHENERS. 



Thirty-five specimens of arrow-smootheners were taken 

 up out of the material of the mounds (Figs. 25, 26.) 

 These were all made from Dakota sandstone. Only five 

 seem to be entire specimens. Of thirty broken ones 

 quite a number show unmistakable evidence of having 

 been used after they were broken. In one instance two 



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