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Archaeology/Native American stone tools


Trio of stones
Trio of stones  
Large granite stone
Large granite stone  
QUESTION: Dr. Salier,
My ancestors settled in southeast SouthDakota and southwest Minnesota and the largest stone was found on private property by a small lake in that area. It looks like granite to me and had a smooth feel to it. There are a few slight depressions that look worn and a couple of very light scratches that look more recent. When set on a flat surface, the stone seems to be stable and doesn't rock as if both sides are worn just flat enough to prevent movement, but barely visible and not very noticible to the touch. At first I thought it couldn't be a grinding stone because ther were no worn/flattened areas, but when I set it on the table it held steady without spinning or rocking.
In your opinion do you think it is a Native American grinding tool or something else?
Also if it is do you have an estimate as to how old it is or from what era?

The smaller grey stone was found in a plowed field and has some deeper scratches that are worn, but it has an interesting feel in the hand. The other round granite stone has more texture to it but it seems worn also.
Thanks for your time!  Jill

ANSWER: Hi Jill,  These appear to be glacially worn cobles which are not uncommon from those areas.  The Ice from the Ice Ages did cover these areas with ice a mile or two thick.  They ground stones like this to very smooth textures and droped them every where as the ice retreated at the end of the ice age.  Our clever Native Americans did use these for some purposes.  

The large one with the flat bottom may have been used as a grinding stone but it looks very heavy and this would make it impractical for use.  However, if there are depressions on the top, it may have been used as a "nutting" stone where a nut would have been placed in the depression and then cracked open with another stone.  But it is difficult to see any depressions on the surface.  Most are at least 1/2" deep to keep the nut from rolling away.

The others are about the size of "manos" or hand held grinders but with out seeing both sides, this is hard for me to determine.  If there is a smooth surface with a bit of polish to it, then these may have been used for grinding corn or other grains.  So, if you could take pics of the bottom sides of these and some that are angled to show the reflections of light from their surfaces, it would be easier for me to make this determination.


---------- FOLLOW-UP ----------

Side 1
Side 1  

Side 2
Side 2  
QUESTION: Thanks, here are the two opposite sides of the largest stone. I set it on a wet towel to show the flattened areas. They are very subtle though. The smaller round stone only has one very slightly flattened spot, so it probably is just a rock. I have enjoyed researching these and appreciate your work, Thanks again.

Hi Jill,  Thank you for sharing your finds with me.  Since you are interested in Archaeology, why not join your local state Archaeological Society?  Check with your local university with a department of Anthropology and chances are someone can point you in the right direction.  If you can't find someone locally, let me know and I'll just need your state and county.  


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Ralph Salier


Archaeologist for the last 30 years. Norh American generalist and Hopwell culture/Red Ocher culture specifically. Lithics Expert and Ground Stone tools.


Past/Present clients
Numerous museums in US and Canada. Several University Anthropology Departments.

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