This is not a SFW instance. NSFW communities will be tagged, and efforts will be made to keep SFW communities clean, but proceed at your own comfort level.
To me it looks like a tree fork. A cross section somewhere above the B and below the AW in the picture below. And I think the darker area in the middle is the heartwood of the main trunk.
Would that be caused by a fire? Do you know of there were forest fires in the area ~20 years ago?
Maybe not, considering there’s a similar discoloring along the outside, but I’m hoping an arborist will chime in.
To me it looks like a tree fork. A cross section somewhere above the B and below the AW in the picture below. And I think the darker area in the middle is the heartwood of the main trunk.
When the tree wasn’t good enough.
I was wondering about that myself.