I further googled about John Jones, who is the guy who died. If you look at my map, he was apparently stuck
Down the Big Slide, at the point of the map that is farthest to the top. It's not where I was thinking at all. In fact, it kind of has me freaked out because I believe I've been down that very spot. On the linked thread I posted about shimmying down a hole, and that's right where it was.