In reply to Tigger:
Just had another look in the slate rock fax. I think you might be thinking about the opposite side of Mordor where Maupin Rey went. The area I saw yesterday was the big wall above and the right of the tunnel that takes you to the base of the lost world. The debris has covered a section of the horseshoe shaped path that leads from the base of the ladders coming down from the khyber pass round to the triple ladders to descend to the base of Mordor.
There are some big undercut lumps of slate left high on the wall which threaten the path used by Snakes and Ladders if I remember correctly.