On Mt Arthur, possibly around the summit cairn, possibly somewhere on the summit plateau, most likely between the plateau edge and the highest scree section.
Volume one of the Abels. You can tell it's mine because of the business cards (exhaust repairs) and chocolate wrappers used as page markers . . .
Will probably be mush by the time anyone stumbles upon it, but you never know.
And the compass - a standard Suunto (I think) plotting compass, no scratches, no string, no bells & whistles, on Hyperion. Somewhere between the summit and the top of the boulder scramble on the moraine. The string broke. That was a sod of a summit - GPS & camera batteries went flat during the last scramble, the compass went walkabout, the wind nearly blew me back down into Helios . . .