We went out today to take a look at a site in the Yorkshire Wolds where there is some ridge and furrow marks in a field. There are a few places in East Yorkshire like this, though they tend not to be quite as prominent as areas in the Midlands. The sun was quite low in the sky and the shadows cast across the field were just about good enough to see the furrows.
These marks were made by ploughs that couldn't turn its face round like modern ploughs do. All of the earth that was turned over by ploughing over very many years formed a bank in one part and a trough in another. The only ones that survive today are where the land has only been used for grazing since medieval ploughing stopped and not touched with a modern plough, so most of these marks are hundreds of years old, some over a thousand years old.
I could put it on the OSM map (I'd have to invent a tag but so what), but I choose not to because such archaeological sites get pillaged by treasure hunters with metal detectors so I don't want to encourage them.