My least exciting guess is that it's just a pile of rocks, and the skid tracks are a result of them be pushed by glaciers (not that I really know anything about geology, fyi)
I wouldn't be surprised at the "new stone-henge" hypothesis, ancient humanity seems to have a knack for making enegegmatic but seemingly useless structures.
That said, it would be awesome if it was alien in origin - if it were, it'd be a probe, though, because a race advanced enough to send a manned craft that small to alien planet would probably know how to hide from the natives.