Laurence, I've had the same wonderings on numerous occasions.
I think mine's obvious - Yosemite. Specifically, this was my first trip up Yosemite Falls. Pic is from the top of the falls, Glacier Point just off right edge, Half Dome across, and I think, the Clark range is what's visible behind/right of Half Dome in the distance. Red Peak is behind & left of Glacier Pt.