Bighorn Canyon, Montana
I came across this pile of rocks when I was bushwhacking down a canon. It looks man-made, almost like an ancient Irish portal tomb or dolmen, but it was just part of a random pile of big boulders blocking my way in the canyon. It would have been a perfect, easy, stand-up walk through the blockage except for the log that had lodged in the middle of the passage during some high-water flood. So instead I had to either crawl under the log or scramble up and over the boulder pile to get to the other side. I chose the latter.