Parts of some USA trails (and presumably others) are marked only by rock cairns, typic'ly when the ground is entirely rock. Downside is, since they don't look l

Parts of some USA trails (and presumably others) are marked only by rock cairns, typic'ly when the ground is entirely rock. Downside is, since they don't look like any kind of official trailmarker, people keep having to be told not to knock them over, not to move them, not to make more…and there are never enough watchers.