Failing to find a photo of the ridge that is said to be Unktehi, I came across "Fossil legends of the first Americans" by Adrienne Mayor in Google books, searching the phrase " Unktehi's bones."
Mayor writes: "Near Fort Snelling above the Minnesota River, the Indians pointed out a mound said to contain Unktehi bones...(Page 234)"
The page before alludes to the "diety" being able to manifest itself as a buffalo, while the next few pages suggest that the bones are those of mastadons.
So maybe my post: Could it be a Mastadon? could just as well be titled "Could it be Yet Another Uktena?"