(Sorry for the low image quality, these are older cell phone photos.)

This is a carved limestone rock found at the top of a mountain peak in middle Tennessee.
This rock is on private land, and as such I can not reveal the exact location other than to say that it lies on the Eastern Highland Rim of Tennessee.
It appears to have been there hundreds or maybe thousands of years.
The landowner says it was here when his grandfather came to the area in the 1800's
It is not a millstone.
The area that looks like a hole in the center is not a hole at all but a bowl shaped depression appearing on only the upper surface of the rock.
There is no water source or stream beds in the area. There are no other structures in the area. The location is more than a mile up a VERY steep climb from the nearest road.
Surrounding the round rock are other much larger rocks of the same composition in a somewhat jumbled circle. The stone disk and surrounding rocks appear to be of a different composition than the other outcroppings on the same mountain.

The landowner believes this rock is the center of a ceremonial location by the Cherokee or other Indians. Says his grandfather told him that when he was a little boy, by the way he is now over 80 years old. However this explanation does not correlate with what I know about the Cherokee Indians in the area.

Any Ideas?

