Frank Florence: "Given RG's clues and the view of Skytop, I'm guessing that the face the climber (RG himself?) is on is Sleepwalk.
The slide may have faded colors, but it looks like it started out showing a steely sky, snow on the distant hills, and a wool cap sur la tete de l'alpinist. What month was that?"
Frank has the climber right, but not the climb, which is further down still. I think the month was February---neither the snow nor the "steely sky" is an artifact of the fading process, and la tete de l'alpinist is indeed shod in wool---but we're talkin' 40 years ago again, so I could easily be wrong about the month, if not the season.