Quantitative measurement of the "field clearing hypothesis"

I never pulled it off but have always believed it would not be hard to prove a field clearing pile had (relatively) random sized rocks - a uniform probability distribution for the different rock sizes. I stumbled over my inability to measure single rocks. When I first thought about it, I also realized that an excessive number of small flat rocks could be a signal for field clearing. Just now, I heard another one: that the collection of piles making up a field clearing pile "site" is itself a mess: piles of different shapes, piles of different sizes, piles on top of each other, piles with large, medium, or small rocks. It is not hard to see when a site is from field clearing.