More Self-Organized Criticality

I know some of you will find it hard to believe, but I used to love raking the leaves around the house where I grew up. Well, earlier today I returned to the old abode and found some leaves to pick up. I noticed the wind swirled in such a way as to create small piles of leaves, on the concrete that is. I could have easily said "Thank you God" but I was thinking about complexity instead. Self organization is one of the hallmarks of complexity theory and here was an example of it staring me straight in the face. My only gripe is why nature just stops half-way and doesn't finish the job by throwing them away in the cuttings container. I guess this is the criticality point. What a bummer!