Rock Glaciers: moving masses of rocks (instead of ice) slowly descending a mountain.
The Rock Glacier Trail is a short and informative interpretive walk in the Kluane National Park and Reserve. The trail starts along a boardwalk and moderately climbs to views of Dezadeash Lake and the surrounding valley.
Rock cairn on Rock Glacier Trail — Kluane National Park and Reserve, Yukon Territory
White Postcards 
When piled rocks are your friends! Great photo. –Curt
Rock stacking can be controversial but I still appreciate a well-placed cairn. -Ginette
I used a special combination of rocks when I led 100 mile mile backpack treks, Ginette. I had my rear guard kick the stones over when all of the trekkers had passed. I allowed people to travel at their own pace and this kept them from getting lost. –Curt