Here is what I found under the berry bushes - whole mature trees we hadn't seen before. That 2 x 6 brace looks like grandpa's effort since he was a professional engineer, and 50 years ago he reinforced many overstressed limbs this way. He died in 1963. This tree may have been buried under blackberries ever since then.
Along this steeper bank I couldn't push bushes from the upper terrace all the way down to the lower terrace so I had to snag what I could from the lower terrace. In this spot, after pushing from the top I could only use the side of the bucket to drag stuff down, because the lower terrace was too narrow to turn facing the slope.