Pile of rocks reprise

You've seen this picture before! But I thought I'd share a passage I came across today while reading Jules Verne's A journey to the center of the earth:

Occasionally he would take it into his head to stop to pick up lumps of rock, and silently pile them up into small heaps, in order that we might not lose our way on our return.

When we took the hike to Skogarkot from Thingvellir these rock piles extended to the horizon, each one just barely in view of the previous one, silent guideposts. We also saw these on the volcanic highlands near Lake Myvatn. Strange to think that this practice has been going on for hundreds, probably a thousand years, maybe more.