Frost and sun

This is the field I blipped a week or two ago after exploring it and seeing an interesting old stone wall/possibly ruins of a stone building (?) https://www.blipfoto.com/entry/2917966199629286547

I went back again partly to have another look at it more closely. I still couldn't decide what the wall is the remains of though. It's interesting how the tree is partly encircled by the stone wall. I imagine the tree didn't come first. 

In the first extra you can see a close up of part of the wall, with what looks like a piece from some sort of old metal machinery. I thought I'd put it up here in case anyone might have an idea about what this metal thing, (or indeed the stone structure) could be. 

Incidentally, the Blip site decided not to show the photos that I back-blipped yesterday. They were there in my journal but not showing up on the 'Follow' page, so no-one would have noticed them. I saw the same thing had happened to fairyhedgehog that day and a couple of other people I follow. Don't know what caused that to happen. I expect it's another mystery we might not solve! ;-)