Found this photo online and got permission from Todd Fonstad to reproduce it. He writes:
Just give credit to the Carl Guell slide collection at the . ...Unfortunately, many of his aerial photos are somewhat blurry due to air speed.
I wanted to comment that I do not think these are all farmer's field clearing. Click to magnify and look at the curved line of small rock piles leading up to the larger one in the upper left of the photo. That looks too geometric to be the result of random rock disposal. More generally, I am fascinated with this photo and what it suggests.