Forest Park Witness Tree

In 1845 a surveyor chose this bur oak to mark the land, and it is still here to be found. The E.S. Harris survey of that year used it as a witness tree: a living survey point, often fixed to establish a corner, so the line could be found again. Surveyors picked such trees for staying power, durable and slow to rot. Bur oak was a favourite, because it lives long and stands up to fire. The reasoning held. The oak had a partner, a second witness tree from the same survey, which stood beside it until 2014, when it was removed after drought and the stresses that came with it. This one is still in Forest Park, more than 180 years after it went into the record. That is also the floor for its age. It was standing in 1845, so it is at least 180 years old, and a tree chosen as a durable landmark was presumably no sapling even then. Nobody has put a firmer number on it. If you know its girth, tell us, and the range can get a top end.