There's pin placement guesses, and then there's this...pure speculation, but in 1958 there was a pasture on Perryville Road (bordering the county line) between the farmsteads in photos 20 and 22. Many years before this photo, a branch of the Milwaukee Road railroad ran diagonally across the pasture, which bordered the photo 20 farmstead to the north. Maybe the explorers in this photo were looking at the remains of the old railroad spur, which ran from Aurora to the old Camp Grant in Rockford. By the 1940s, the rail line had already been removed, and a couple of trees were still growing in the pasture along the former roadbed in 1958 aerial images. Perhaps the tree in this photo was one of those.