Amazing how the tree grew and lifted the rocks out of the wall that was below it. The wall has since fallen down. I must point out that the rocks are about 12 inch cubed. The wall was built next to a coal transport railway line in about 1830-40. The tree is not as old. I have walked the most of the railway line, which is now a cycle path from Newport to Blaenavon in South-East Wales (UK) and while there are many old walls, this is the only one that I have seen.
See my Odds Gallery for more images.