When we moved into our present home about 14 years ago there was this large dead oak tree at the edge of our yard. The tree was leaning into the yard and I was certain it would be falling at any time. If it fell in the yard that would mean I would have to cut it up and remove. Work.
So, to avoid the work I notched and cut it to fall into the woods. It has lain there all this time. Not knowing how long it takes a deadfall to rot and become soil, I went out and checked this one. Very surprised to see it has rotted about 2-3 inches and inside seems to be solid still.
Not sure what good this bit of info is but somewhat interesting.