Not saying Bigfoot did this but on occasion I been seeing allot of large rocks turned over. It could be a bear this one is not as large but up at Kings Canyon there was one much deeper and thrown off a cliff leaving a hole similar to this one. Only difference is the rock is laying to the left of it. It could be something Bigfoot might do or like I said a black bear learning for bugs perhaps. More importantly with all the big rocks, old trees and dense foliage anything could use this place as if it were a primates playground.