We were back in our square today, and we made more progress on defining that stone feature. The trailing line of stones that you'd expect to see on the left of my square has been taken out; it does seem to me that it was some of the missing stones from what we're excavating, but it'll take more digging to know if that's true -- if the feature itself is a lot deeper, I may have to come up with a different theory.
However, while those stones are gone, more are cropping up. There's a group of four stones to the right of the feature that are particularly interesting. It's possible that they're just later fill, or rocks which have happened to fall when there was a surface somewhere around there. But there are four of them, and they look sort of like their in a square. That's a lot of rocks, and a shape that can mean all sorts of thing.
My suspicion is that we'll learn more about them tomorrow.