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A hollow way in La Meauffe, Manche, France
(sh.itjust.works)
Desire paths Desire paths can be paths created as a consequence of erosion caused by human or animal foot-fall or traffic. The paths usually represent the shortest or most easily navigated routes between origins and destinations. https://en.wikipedia.org/wiki/Desire_path
This is what centuries old desire paths look like. Or it's an old (non-standard?) railway.