That appears to be some very fine bunker edging work, and much nicer than I would have believed for 1941. Also, the MacKenzie bunkers are really cool, and most interesting how the slope down inwards towards the green with a healthy amount of fringe collar between the bunker and putting surface. Does anyone have an idea of what kind or amount of drainage line is under there to keep the rain from running down into the green? Were washouts of the bunkers an issue?