This is somewhat damaged but still a magnificent construction. It was on a little ridge overlooking the beginning of water flow from a hill. But the opening of the seat was uphill. Here is a view of the opening:
And here is a view from the other side:
I would like to get some of the archeologists to explain what this could possibly have to do with field clearing. The study of rock piles begins with the observation that there are other types of piles besides field clearing ones. For example ones like this with structure and made of lburnt ledgerock.