My five year old makes rock piles like that. It is her "collection". Do you have precocious grandkids?
Ranger,
Nope, not a child withing miles.
And it happened more than once after I kicked them off the pavement. I finally got tired and actually got the broom out. Piles came back soon after, only neater!
Geno
PS, ALIENS I tell ya'
The desert is a true treasure for him who seeks refuge from men and the evil of men. In it is contentment In it is death and all you seek (Quoted from "The Bleeding of the Stone" Ibrahim Al-Koni)